尝试一下:

Public static void ReplaceTextInExcelFile(string filename, string replace, string replacement)
{
    object m = Type.Missing;

    // open excel.
    Application app = new ApplicationClass();

    // open the workbook. 
    Workbook wb = app.Workbooks.Open(
        filename,
        m, false, m, m, m, m, m, m, m, m, m, m, m, m);

    // get the active worksheet. (Replace this if you need to.) 
    Worksheet ws = (Worksheet)wb.ActiveSheet;

    // get the used range. 
    Range r = (Range)ws.UsedRange;

    // call the replace method to replace instances. 
    bool success = (bool)r.Replace(
        replace,
        replacement,
        XlLookAt.xlWhole,
        XlSearchOrder.xlByRows,
        true, m, m, m);

    // save and close. 
    wb.Save();
    app.Quit();
    app = null;
}