Hike Mutianyu - Simutai- possible?

Hi, Kim. It's impossible to hike from Mutianyu to Simatai since these two parts are far away from each other. If you want to hike on two sections, you are suggested to visit Jiankou and Mutianyu Great Wall which are connected. This trip will take 2 days.
In the first day, you could take a train from Chengde to Huairou Station, and walk for 200m to Huairou Bus Station. Then take bus no.936 to Yanqizhen Station, and take bus no.h25 to Xizhazi Station. Upon arrival, you may find the 5th Team of Xizhazi Village directly. The train and the bus drive takes about 7 hours. In the afternoon you could visit north part of Jiankou Great Wall including Beijing Knot and Eagle Flies Facing Upward. After your visit, you are suggested to stay at the 5th Team of Xizhazi Village for a night.
In the next morning, you could go hiking to the south part of Jiankou Great Wall including Sky Stair, Jiankou Spot and Ox Horn Edge and you could directly go to Mutianyu Great Wall from Jiankou to east.
After your trip to Mutianyu you could take bus Qianmen/Dongzhimen tourist line at P1 parking lot to Qianmen or Dongzhimen Transportation Hub in Beijing. These buses depart respectively at 15:30 and 16:00 everyday.