You can take the train to Mount Wutai. The cities of Taiyuan and Jinzhong have direct trains to Mount Wutai. If you go to Mount Wutai by train from Beijing, you have to transfer to Mount Wutai in Taiyuan.
From Dingzhou to Mount Wutai? Sit in Taiyuan and then transfer to a car. <br/>In addition, don't be misled by the so-called "Wutaishan Railway Station", that railway station is not in Wutai at all!