Aimed at the shortcomings that a single seal ring is easy to wear and cause seal failure,and the process of replacing the seal is difficult,a multiple combined sealing structure was designed.On the basis of the existing sealing structure with a single sealing ring,two cushioning sealing rings were arranged inside the piston rod,and a sealing ring was added at the bottom of the cylinder to form a multiple combined sealing structure.Through finite element simulation,the maximum bearing capacity and the extrusion deformation of the seal ring in the single sealing ring structure and multiple combined sealing structure were analyzed when the sealing ring moves with the piston rod reciprocating under uniformly distributed different pressures.The changes in the service life and stress concentration area of the seal ring were also explored.The results show that the multiple combined sealing structure can effectively reduce the pressure of sealing ring.The seal ring has no obvious extrusion wear during use,and its service life is extended,which verifies the effectiveness and feasibility of the multiple combined sealing system.