diff --git a/Better-EN5/Services/Conversion/EnbxReader.cs b/Better-EN5/Services/Conversion/EnbxReader.cs
index 42fd4f6..208170d 100644
--- a/Better-EN5/Services/Conversion/EnbxReader.cs
+++ b/Better-EN5/Services/Conversion/EnbxReader.cs
@@ -10,6 +10,7 @@ namespace BetterEN5.Services.Conversion
 {
     public class EnbxReader
     {
+        private static readonly XNamespace Rel = "http://schemas.openxmlformats.org/package/2006/relationships";
         private int _nextId;
 
         public SmfDocument Import(string enbxPath)
@@ -29,7 +30,7 @@ namespace BetterEN5.Services.Conversion
             if (docPart != null)
             {
                 var docXml = XDocument.Load(docPart.GetStream());
-                ParseDocumentXml(docXml, doc, enbx);
+                ParseDocumentXml(docXml.Root ?? throw new InvalidOperationException("Missing document root"), doc, enbx);
             }
             else
             {
@@ -67,7 +68,7 @@ namespace BetterEN5.Services.Conversion
 
             var relsPart = enbx.GetPart(relsUri);
             var rels = XDocument.Load(relsPart.GetStream());
-            foreach (var rel in rels.Root?.Elements("Relationship") ?? Enumerable.Empty<XElement>())
+            foreach (var rel in rels.Root?.Elements(Rel + "Relationship") ?? Enumerable.Empty<XElement>())
             {
                 var type = (string)rel.Attribute("Type") ?? "";
                 if (type.Contains("document") || type.Contains("officeDocument"))
@@ -83,8 +84,8 @@ namespace BetterEN5.Services.Conversion
 
         private void ParseDocumentXml(XElement docXml, SmfDocument doc, Package enbx)
         {
-            var root = docXml.Root ?? docXml;
-            var enNs = root.GetDefaultNamespace();
+            var root = docXml;
+            var enNs = root.Name.Namespace;
 
             var props = root.Element(enNs + "Properties");
             if (props != null)
@@ -153,7 +154,7 @@ namespace BetterEN5.Services.Conversion
 
         private void ParseSlideXml(XDocument slideXml, SmfDocument doc, int slideNum)
         {
-            var root = slideXml.Root ?? slideXml;
+            var root = slideXml.Root ?? throw new InvalidOperationException("Missing slide root");
             var enNs = root.GetDefaultNamespace();
             var slide = new SmfSlide { Id = $"slide_{slideNum}" };
 
diff --git a/Better-EN5/Services/Conversion/PptxImporter.cs b/Better-EN5/Services/Conversion/PptxImporter.cs
index d3a336e..c284b30 100644
--- a/Better-EN5/Services/Conversion/PptxImporter.cs
+++ b/Better-EN5/Services/Conversion/PptxImporter.cs
@@ -12,6 +12,7 @@ namespace BetterEN5.Services.Conversion
         private static readonly XNamespace A = "http://schemas.openxmlformats.org/drawingml/2006/main";
         private static readonly XNamespace P = "http://schemas.openxmlformats.org/presentationml/2006/main";
         private static readonly XNamespace R = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
+        private static readonly XNamespace Rel = "http://schemas.openxmlformats.org/package/2006/relationships";
 
         private int _nextId;
 
@@ -33,9 +34,11 @@ namespace BetterEN5.Services.Conversion
             ExtractMediaFiles(pptx, doc);
 
             var slideRels = GetSlideRelations(pptx, pres);
+            var presPartUri = PackUriHelper.CreatePartUri(new Uri("/ppt/presentation.xml", UriKind.Relative));
             foreach (var (relId, target, slideNum) in slideRels)
             {
-                var slidePart = pptx.GetPart(PackUriHelper.CreatePartUri(new Uri(target, UriKind.Relative)));
+                var resolvedUri = PackUriHelper.ResolvePartUri(presPartUri, new Uri(target, UriKind.Relative));
+                var slidePart = pptx.GetPart(resolvedUri);
                 var slideXml = XDocument.Load(slidePart.GetStream());
                 var slide = new SmfSlide { Id = $"slide_{slideNum}" };
 
@@ -100,7 +103,7 @@ namespace BetterEN5.Services.Conversion
                     if (relsPart != null)
                     {
                         var rels = XDocument.Load(relsPart.GetStream());
-                        var rel = rels.Root?.Elements("Relationship")
+                        var rel = rels.Root?.Elements(Rel + "Relationship")
                             .FirstOrDefault(r => (string)r.Attribute("Id") == embed);
                         if (rel != null)
                         {
@@ -228,7 +231,7 @@ namespace BetterEN5.Services.Conversion
             var relsPart = GetSlideRelsPart(pptx, slide.Id);
             if (relsPart == null) return;
             var rels = XDocument.Load(relsPart.GetStream());
-            var rel = rels.Root?.Elements("Relationship")
+            var rel = rels.Root?.Elements(Rel + "Relationship")
                 .FirstOrDefault(r => (string)r.Attribute("Id") == embed);
             if (rel == null) return;
 
@@ -731,7 +734,7 @@ namespace BetterEN5.Services.Conversion
             var relsUri = PackUriHelper.CreatePartUri(new Uri("/_rels/.rels", UriKind.Relative));
             var relsPart = pptx.GetPart(relsUri);
             var rels = XDocument.Load(relsPart.GetStream());
-            var officeRel = rels.Root?.Elements("Relationship")
+            var officeRel = rels.Root?.Elements(Rel + "Relationship")
                 .FirstOrDefault(r => (string)r.Attribute("Type") ==
                     "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument");
             if (officeRel == null) throw new InvalidDataException("未找到 Office Document 关系");
@@ -774,7 +777,7 @@ namespace BetterEN5.Services.Conversion
                 }
             }
 
-            var relDict = rels.Root?.Elements("Relationship")
+            var relDict = rels.Root?.Elements(Rel + "Relationship")
                 .Where(r => (string)r.Attribute("Type") == slideType)
                 .ToDictionary(r => (string)r.Attribute("Id"), r => (string)r.Attribute("Target"));
 
diff --git a/Manager/Services/Conversion/EnbxReader.cs b/Manager/Services/Conversion/EnbxReader.cs
index 10dd9f3..e142804 100644
--- a/Manager/Services/Conversion/EnbxReader.cs
+++ b/Manager/Services/Conversion/EnbxReader.cs
@@ -10,6 +10,7 @@ namespace BetterSeewo.Manager.Services.Conversion
 {
     public class EnbxReader
     {
+        private static readonly XNamespace Rel = "http://schemas.openxmlformats.org/package/2006/relationships";
         private int _nextId;
 
         public SmfDocument Import(string enbxPath)
@@ -67,7 +68,7 @@ namespace BetterSeewo.Manager.Services.Conversion
 
             var relsPart = enbx.GetPart(relsUri);
             var rels = XDocument.Load(relsPart.GetStream());
-            foreach (var rel in rels.Root?.Elements("Relationship") ?? Enumerable.Empty<XElement>())
+            foreach (var rel in rels.Root?.Elements(Rel + "Relationship") ?? Enumerable.Empty<XElement>())
             {
                 var type = (string)rel.Attribute("Type") ?? "";
                 if (type.Contains("document") || type.Contains("officeDocument"))
@@ -84,7 +85,7 @@ namespace BetterSeewo.Manager.Services.Conversion
         private void ParseDocumentXml(XElement docXml, SmfDocument doc, Package enbx)
         {
             var root = docXml;
-            var enNs = root.GetDefaultNamespace();
+            var enNs = root.Name.Namespace;
 
             var props = root.Element(enNs + "Properties");
             if (props != null)
diff --git a/Manager/Services/Conversion/PptxImporter.cs b/Manager/Services/Conversion/PptxImporter.cs
index 33b7068..2053c78 100644
--- a/Manager/Services/Conversion/PptxImporter.cs
+++ b/Manager/Services/Conversion/PptxImporter.cs
@@ -12,6 +12,7 @@ namespace BetterSeewo.Manager.Services.Conversion
         private static readonly XNamespace A = "http://schemas.openxmlformats.org/drawingml/2006/main";
         private static readonly XNamespace P = "http://schemas.openxmlformats.org/presentationml/2006/main";
         private static readonly XNamespace R = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
+        private static readonly XNamespace Rel = "http://schemas.openxmlformats.org/package/2006/relationships";
 
         private int _nextId;
 
@@ -33,9 +34,11 @@ namespace BetterSeewo.Manager.Services.Conversion
             ExtractMediaFiles(pptx, doc);
 
             var slideRels = GetSlideRelations(pptx, pres);
+            var presPartUri = PackUriHelper.CreatePartUri(new Uri("/ppt/presentation.xml", UriKind.Relative));
             foreach (var (relId, target, slideNum) in slideRels)
             {
-                var slidePart = pptx.GetPart(PackUriHelper.CreatePartUri(new Uri(target, UriKind.Relative)));
+                var resolvedUri = PackUriHelper.ResolvePartUri(presPartUri, new Uri(target, UriKind.Relative));
+                var slidePart = pptx.GetPart(resolvedUri);
                 var slideXml = XDocument.Load(slidePart.GetStream());
                 var slide = new SmfSlide { Id = $"slide_{slideNum}" };
 
@@ -100,7 +103,7 @@ namespace BetterSeewo.Manager.Services.Conversion
                     if (relsPart != null)
                     {
                         var rels = XDocument.Load(relsPart.GetStream());
-                        var rel = rels.Root?.Elements("Relationship")
+                        var rel = rels.Root?.Elements(Rel + "Relationship")
                             .FirstOrDefault(r => (string)r.Attribute("Id") == embed);
                         if (rel != null)
                         {
@@ -216,7 +219,7 @@ namespace BetterSeewo.Manager.Services.Conversion
             var relsPart = GetSlideRelsPart(pptx, slide.Id);
             if (relsPart == null) return;
             var rels = XDocument.Load(relsPart.GetStream());
-            var rel = rels.Root?.Elements("Relationship")
+            var rel = rels.Root?.Elements(Rel + "Relationship")
                 .FirstOrDefault(r => (string)r.Attribute("Id") == embed);
             if (rel == null) return;
 
@@ -565,7 +568,7 @@ namespace BetterSeewo.Manager.Services.Conversion
             var relsUri = PackUriHelper.CreatePartUri(new Uri("/_rels/.rels", UriKind.Relative));
             var relsPart = pptx.GetPart(relsUri);
             var rels = XDocument.Load(relsPart.GetStream());
-            var officeRel = rels.Root?.Elements("Relationship")
+            var officeRel = rels.Root?.Elements(Rel + "Relationship")
                 .FirstOrDefault(r => (string)r.Attribute("Type") ==
                     "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument");
             if (officeRel == null) throw new InvalidDataException("未找到 Office Document 关系");
@@ -600,7 +603,7 @@ namespace BetterSeewo.Manager.Services.Conversion
                 foreach (var sldId in sldIdLst.Elements(P + "sldId"))
                     order.Add((string)sldId.Attribute(R + "id"));
 
-            var relDict = rels.Root?.Elements("Relationship")
+            var relDict = rels.Root?.Elements(Rel + "Relationship")
                 .Where(r => (string)r.Attribute("Type") == slideType)
                 .ToDictionary(r => (string)r.Attribute("Id"), r => (string)r.Attribute("Target"));