DataTable dt = new DataTable("dt", "http://baidu.com");
            dt.Prefix = "xs";//前缀
            dt.Columns.Add("id");
            dt.Columns.Add("name");

            DataRow dr = dt.NewRow();
            dr["id"] = "123";
            dr["Name"] = "xs";
            dt.Rows.Add(dr);

            DataRow dr1 = dt.NewRow();
            dr1["id"] = "456";
            dr1["Name"] = "xsdc";
            dt.Rows.Add(dr1);
            //dt.WriteXml("C:\\2.xml");//此方法保存的xml只是datatable,读取时会失败
            dt.WriteXml("C:\\1.xml", XmlWriteMode.WriteSchema);//会在xnl中自动生成新的dataset

            DataTable dt1 = new DataTable("dt");

            dt1.ReadXml(@"C:\\1.xml");

<?xml version="1.0" standalone="yes"?>
<NewDataSet xmlns="http://baidu.com">
  <xs:schema id="NewDataSet" targetNamespace="http://baidu.com" xmlns:mstns="http://baidu.com" xmlns="http://baidu.com" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" attributeFormDefault="qualified" elementFormDefault="qualified">
    <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:MainDataTable="http_x003A__x002F__x002F_baidu.com_x003A_dt" msdata:UseCurrentLocale="true">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="dt" msdata:Prefix="xs">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="id" type="xs:string" minOccurs="0" />
                <xs:element name="name" type="xs:string" minOccurs="0" />
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:complexType>
    </xs:element>
  </xs:schema>
  <xs:dt xmlns:xs="http://baidu.com">
    <id>123</id>
    <name>xs</name>
  </xs:dt>
  <xs:dt xmlns:xs="http://baidu.com">
    <id>456</id>
    <name>xsdc</name>
  </xs:dt>
</NewDataSet>

<?xml version="1.0" standalone="yes"?>
<xs:DocumentElement xmlns:xs="http://baidu.com">
  <xs:dt>
    <id xmlns="http://baidu.com">123</id>
    <name xmlns="http://baidu.com">xs</name>
  </xs:dt>
  <xs:dt>
    <id xmlns="http://baidu.com">456</id>
    <name xmlns="http://baidu.com">xsdc</name>
  </xs:dt>
</xs:DocumentElement>