what is the best way to go from Qufu (Shandong province) to Pingyao (Shanxi probince)? thanks

From Qufu, you can take the bullet train for Jinan West Train Station and then go to Jinan Railway Station where you can find the trains for Taiyuan.
Upon reaching Taiyuan Railway Station, you can take a taxi to reach local Jiannan Bus Station where you can find frequent buses for Pingyao.