I found it for you with great difficulty for your reference.
1, first from Kunshan to Chengdu, just take the train. I didn't check the specific bus, because there will be many buses from Kunshan to Chengdu.
2. There are two flights from Chengdu to Qamdo, Tibet, both of which are Air China, and the voyages are CA4298 and CA4408 respectively. There may be shuttle buses, but they are all mountain roads and you are not allowed to travel.
There is no shuttle bus from Changdu, Tibet to Yushu, Qinghai, but the road is accessible. You can hire a car or carpool. You'd better take a map with you for better navigation.
The route from Changdu to Yushu:
1.？ Depart from the starting point to the southeast, follow G3 17 for 220 meters, turn right and enter G3 17?
2.？ Drive along G3 17107.3km and go straight into G2 14?
3.？ Drive along G2 14 for 382.3 kilometers and reach the destination (right side of the road)?
I hope it helps you. Bon voyage!