Hello, i would like to know if there is a bus every day between Xining and Yushu? and cost?

Yes, there are still several direct long-distance buses that run between these two places.
From XN, the bus schedules from Passenger Transportation Center are 11:00, 12:30, 14:30, 15:30, 16:00, 17:00, 18:00 and 18:30.
From Yushu Bus Station, the buses are available at 08:30, 09:00, 12:00, 13:00, 15:00 and 16:00.
You are suggested to confirm this bus schedule when you arriving at the bus station.