i am staying in mercure hotel,no 16 jia,xi da wang road,chao yang district subway bus to greatwall

From your hotel, you can walk to Dawangqiao Subway Station and take the subway line 1 to Jianguomen Station and then change to subway line 2 to stop at Zhonggulou Station. Then you can walk to Deshengmen Bus station which is on the east of the Deshengmen Arrow Tower to take 919 to the Great Wall directly.