Hi Juan,
Good morning, I am Elian from Topchinatravel, and have received your message about transporting to the train station from the bus station.
Lanzhou South bus station is about 9 km from Lanzhou west train station. There is a direct bus to get to West train station. You can take bus No. 129 at Lanzhou south train station and get off at Lanzhou west dongkou stop. It will take 1 hour on the way and the fare is 1 yuan. Then walk 900 m to reach the station.
If your time is tight, we suggest you take a taxi and the fare is about 30 yuan. It will take 30 minutes.
Wish you have a nice day!
Elian from TCT