hello how can i go to Mutianyu if I'm in beijing west railway station?

Fatima, you can take subway line 9 to National Library (guojiatushuguan), change subway line 4 to Xizhimen station and then take subway line 2 to reach Dongzhimen. Then walk to Donghzimen Transportation Hub to take 916 Express to reach its terminal station and take minivan to reach the wall. This is the fastest way.