/// <summary>
        /// 限制输入数字以外的字符
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void txtRuYuanCount_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (((int)e.KeyChar < 48 || (int)e.KeyChar > 57) && e.KeyChar != 8)
            {
                e.Handled = true;
            }
        }

------解决方案--------------------

没太看清楚你想要的效果到底什么样的。下面应该能满足你需求

如果是按下空格键在文本框中没有任何反应的话，在PreviewKeyUp时间中加入 e.Handled.

       private void Tb_TableName_PreviewKeyDown(object sender, KeyEventArgs e)
       {
           if (e.Key == Key.Space)
           {
               e.Handled = true;
           }
       }