As people’s life quality rise continuously, the fitness industry has developed fast. At present, people mainly focus on the improvement and research of fitness bike’s comfort and security, not on the movement manner. Thus it causes the movement process to be drab and boring, which has negative effect on the exercise. Therefore, Shenzhen Institute of Advanced Technology developed a new kind of multifunctional interactive fitness bike. Its characteristic is that both hands and feet can driver it independently, which can add different movement manners. This paper mainly aims at designing a new kind of resistance automatic adjustment system according to its unique drive mode. This system can make the rider obtain smooth and comfortable feel. At last, through the manufacturing and debugging of the prototype of fitness bike, we know this scheme is feasible.