XmlReader reader = null;
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.IgnoreComments = true;
settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessSchemaLocation;
settings.ValidationFlags |= XmlSchemaValidationFlags.ReportValidationWarnings;
settings.ValidationEventHandler += new ValidationEventHandler(this.ValidationCallBack);
reader = XmlReader.Create(你的文件, settings);

while (reader.Read())
{
......
}

private void ValidationCallBack(object sender, ValidationEventArgs args)
{
    XmlReader reader = (XmlReader)sender;
    if (args.Severity == XmlSeverityType.Warning)
    {
        Console.WriteLine(string.Format("***Warning: {0}\n", args.Message));
    }
    else
    {
        Console.WriteLine(string.Format("***Error: {0}\n", args.Message));
    }
    Console.WriteLine(string.Format("***Value: {0}\n", reader.Value));
    Console.WriteLine(string.Format("***LineNumber: {0}\n", args.Exception.LineNumber));
}