为XmlDocument设置InnerXml会导致缺少结束标记

问题是您正在创建一个XmlWriter,但没有处理它—所以它没有刷新。试试这个:

using System;
using System.Text;
using System.Xml;

class Test
{
    static void Main()
    {
        XmlDocument doc = new XmlDocument();
        doc.AppendChild(doc.CreateElement("Foo"));
        doc.DocumentElement.InnerXml = "Test";      
        StringBuilder result = new StringBuilder();
        using (XmlWriter writer = XmlWriter.Create(result))
        {
            doc.WriteContentTo(writer);
        }
        Console.WriteLine(result);
    }
}

<?xml version="1.0" encoding="utf-16"?><Foo>Test</Foo>