Is there any way to go from Mutianyu G.Wall to Nanshan Ski Resort?

Mirza, there is no direct bus from Mutianyu to Nanshan Ski Resort. If you take public buses, you need to spend around 4.5 hours. And the final bus station is a bit far from the ski resort, probably 2.5 to 3 kilometers.

If you really want to visit the ski resort from Mutianyu, you may take a taxi. It costs around CNY 171. However, I guess that the driver might ask for more money. You need to negotiate with him.