public static void distinct(string filePath)

        {

            //1、创建XML文档对象

            XmlDocument doc = new XmlDocument();

            //2、加载指定路径的XML

            doc.Load(filePath);

            //3、获得根节点

            XmlElement root = doc.DocumentElement;

            //4-1、获得根节点的所有子节点

            XmlNodeList allNodes = root.ChildNodes;

            for (int i = ; i < allNodes.Count - ; i++)

            {

                XmlElement node_Element = (XmlElement)allNodes[i];

                string currentNodeValue = node_Element.GetAttribute("Include");

                for (int j = i + ; j < allNodes.Count; j++)

                {

                    XmlElement node_Element_temp = (XmlElement)allNodes[j];

                    if (node_Element_temp.GetAttribute("Include") == currentNodeValue)

                    {

                        node_Element_temp.ParentNode.RemoveChild(node_Element_temp);

                        j--;

                        continue;

                    }

                }

            }

            doc.Save(filePath);

        }

<?xml version="1.0" encoding="utf-8"?>

<ItemGroup>

  <Compile Include="1" />

  <Compile Include="1" />

  <Compile Include="1" />

  <Compile Include="2" />

  <Compile Include="3" />

  <Compile Include="1" />

  <Compile Include="1" />

</ItemGroup>