diff --git a/pkg/document/document.go b/pkg/document/document.go
index a58011b..f7b7d60 100644
--- a/pkg/document/document.go
+++ b/pkg/document/document.go
@@ -15,6 +15,11 @@ import (
 	"github.com/zerx-lab/wordZero/pkg/style"
 )
 
+const (
+	wordprocessingMLNamespace       = "http://schemas.openxmlformats.org/wordprocessingml/2006/main"
+	wordprocessingMLStrictNamespace = "http://purl.oclc.org/ooxml/wordprocessingml/main"
+)
+
 // Document 表示一个Word文档
 type Document struct {
 	// 文档的主要内容
@@ -2016,21 +2021,42 @@ func (d *Document) parseDocument() error {
 
 		switch t := token.(type) {
 		case xml.StartElement:
-			if t.Name.Local == "document" && t.Name.Space == "http://schemas.openxmlformats.org/wordprocessingml/2006/main" {
+			if isWordprocessingDocumentElement(t) {
 				// 开始解析文档
 				if err := d.parseDocumentElement(decoder); err != nil {
 					return err
 				}
 				goto done
 			}
+			if t.Name.Local == "document" {
+				return WrapError("parse_document", fmt.Errorf("%w: unsupported document namespace %q", ErrInvalidDocument, t.Name.Space))
+			}
 		}
 	}
 
+	return WrapError("parse_document", fmt.Errorf("%w: missing document root", ErrInvalidDocument))
+
 done:
+	if d.Body == nil {
+		return WrapError("parse_document", fmt.Errorf("%w: missing document body", ErrInvalidDocument))
+	}
 	Infof("解析完成，共 %d 个元素", len(d.Body.Elements))
 	return nil
 }
 
+func isWordprocessingDocumentElement(start xml.StartElement) bool {
+	if start.Name.Local != "document" {
+		return false
+	}
+
+	switch start.Name.Space {
+	case wordprocessingMLNamespace, wordprocessingMLStrictNamespace:
+		return true
+	default:
+		return false
+	}
+}
+
 // parseDocumentElement 解析文档元素
 func (d *Document) parseDocumentElement(decoder *xml.Decoder) error {
 	// 初始化Body
diff --git a/pkg/document/document_test.go b/pkg/document/document_test.go
index c8e54f3..f044f57 100644
--- a/pkg/document/document_test.go
+++ b/pkg/document/document_test.go
@@ -1,6 +1,10 @@
 package document
 
 import (
+	"archive/zip"
+	"bytes"
+	"errors"
+	"io"
 	"os"
 	"testing"
 
@@ -958,6 +962,77 @@ func TestDocumentOpenFromMemory(t *testing.T) {
 	}
 }
 
+func TestDocumentOpenFromMemoryWithStrictNamespace(t *testing.T) {
+	files := buildTestDocxReader(t, `<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<w:document xmlns:w="http://purl.oclc.org/ooxml/wordprocessingml/main">
+  <w:body>
+    <w:p>
+      <w:r>
+        <w:t>Strict 文档</w:t>
+      </w:r>
+    </w:p>
+  </w:body>
+</w:document>`)
+
+	doc, err := OpenFromMemory(files)
+	if err != nil {
+		t.Fatalf("Failed to open strict namespace document: %v", err)
+	}
+
+	paragraphs := doc.Body.GetParagraphs()
+	if len(paragraphs) != 1 {
+		t.Fatalf("Expected 1 paragraph, got %d", len(paragraphs))
+	}
+
+	if got := paragraphs[0].Runs[0].Text.Content; got != "Strict 文档" {
+		t.Fatalf("Expected strict namespace text to be parsed, got %q", got)
+	}
+}
+
+func TestDocumentOpenFromMemoryWithInvalidRootReturnsError(t *testing.T) {
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("OpenFromMemory should return an error instead of panicking: %v", r)
+		}
+	}()
+
+	files := buildTestDocxReader(t, `<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<document xmlns="https://example.com/custom-wordprocessingml">
+  <body/>
+</document>`)
+
+	_, err := OpenFromMemory(files)
+	if err == nil {
+		t.Fatal("Expected invalid document root to return an error")
+	}
+
+	if !errors.Is(err, ErrInvalidDocument) {
+		t.Fatalf("Expected ErrInvalidDocument, got %v", err)
+	}
+}
+
+func buildTestDocxReader(t *testing.T, documentXML string) io.ReadCloser {
+	t.Helper()
+
+	var buf bytes.Buffer
+	zipWriter := zip.NewWriter(&buf)
+
+	fileWriter, err := zipWriter.Create("word/document.xml")
+	if err != nil {
+		t.Fatalf("Failed to create document.xml entry: %v", err)
+	}
+
+	if _, err := fileWriter.Write([]byte(documentXML)); err != nil {
+		t.Fatalf("Failed to write document.xml entry: %v", err)
+	}
+
+	if err := zipWriter.Close(); err != nil {
+		t.Fatalf("Failed to close test DOCX writer: %v", err)
+	}
+
+	return io.NopCloser(bytes.NewReader(buf.Bytes()))
+}
+
 // TestAddPageBreak 测试添加分页符功能
 func TestAddPageBreak(t *testing.T) {
 	doc := New()