<?xml version="1.0" encoding="utf-8" ?> 
<mai xmlal="int">2</mai> 

 string xmlFilename = "XmlDocument.xml";

    // Use WriteXml to write the document.
    OriginalDataSet.WriteXml(xmlFilename);

    // Dispose of the original DataSet.
    OriginalDataSet.Dispose();

    // Create a new DataSet.
    DataSet newDataSet = new DataSet("New DataSet");

    // Read the XML document into the DataSet.
    newDataSet.ReadXml(xmlFilename);

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顶楼上，msdn有例子

------解决方案--------------------

XmlDocument xmlDoc=new XmlDocument();
xmlDoc.Load(@"路径");
用xmlDoc.DocumentElement.InnerXml得到。