To the problems of difficult to meet the complex parts structure manufacturing of a circular belt drive mechanical transmission on the time-varying transmission ratio and specific output requirements,a non-circular belt drive mechanism of variable speed is designed,the kinematics analysis of the transmission mechanism is carried out,and compared with the circular belt transmission mechanism.The results show that a non-circular belt drive mechanism can achieve different movement according to the specific parameters of the output curve,the vibration and shock of non-circular belt transmission mechanism is greater than the circular belt drive mechanism,the design of non-circular belt drive mechanism can provide a basis for the design of the belt drive mechanism of variable speed and special belt drive mechanism.