Abstract:The precision ball planetary reducing mechanism is a type of highefficiency and energysaving cycloidal transmission mechanism. Here, a twostage cycloidal ball planetary transmission mechanism (CBPTM) is designed, which employed the deceleration balls as the transmission mediumand achieved the gapless meshing transmission in a circulating raceway formed by the epicycloid groove and the hypocycloid groove. The transmission principle of the planetary reducing mechanism is analyzed, and the transmission ratios of different types of the CBPTM are calculated. Based on the platform of automatic dynamic simulation software ADAMS, the kinematics simulation of the twostage CBPTM is conducted, meanwhile, the angular velocity, angular acceleration curves of the planetary disc and the cycloidal disc during the movement process have been obtained. The smoothness of motion and transmission rationality of the deceleration mechanism have been verified and analyzed, which provides the basis for the structural optimization and transmission ratio design for the twostage cycloidal ball planetary reducing transmission.