关闭已创建但从未保存的Microsoft WORD文档

这似乎有效。。。你的问题中有没有特别要求?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using Word = Microsoft.Office.Interop.Word;
using Office = Microsoft.Office.Core;
using Microsoft.Office.Tools.Word;

namespace WordAddIn1
{
  public partial class ThisAddIn
  {
private void ThisAddIn_Startup(object sender, System.EventArgs e)
    {
      var app = Application;
      var doc = app.Documents.Add(Visible: false);

      doc.Close();

      var docCount = Application.Documents.Count ; // =0
    }

    private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
    {
    }

    #region Von VSTO generierter Code

    /// <summary>
    /// Erforderliche Methode für die Designerunterstützung.
    /// Der Inhalt der Methode darf nicht mit dem Code-Editor geändert werden.
    /// </summary>
    private void InternalStartup()
    {
      this.Startup += new System.EventHandler(ThisAddIn_Startup);
      this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
    }

    #endregion
  }
}