I Must go from the rong Chang East Station to the boxing lu road (Beijing Benz). Which Bus line?

You can take public bus No. Development District 3 at East Rongchang Street Metro Station, get off at Benz Bus Stop. Then walk east along Qinhe 2nd Street around 430 yards (390 meters) to arrive at the destination.
Or for your convenience, you can also take a taxi directly. The cab fare is about CNY 15 in the day time. :)