Hello，Mrs.Ema Damayanti：You can take a taxi to the liangmaqiao station of subway line 10,and transfer to
line 1 at the the Guomao station,then transfer to line 2 at the Jianguomen station. Stop at the Changchunjie station. Get off and take a taxi to the Niujie Mosque. Actually, it is not convenient. Take a taxi is right choice, but it's a little expensive,about ￥80-100.