Abstract: A six-degrees-of-freedom parallel mechanism design method is proposed, and this method with constant redundant driving force can be applied to heavy load condition. A dynamical model of redundant parallel mechanism with heavy load is established. Six typical motion states of the redundant parallel mechanism are simulated and optimized, using the upper hinged point coordinate of redundant landing leg and the redundant driving force as input variables and focusing on minimizing the landing leg drive forces. The optimization results show that the load capacity of the platform is increased by 24.02%.