Abstract: Aiming at the problem that the elderly are difficult to get up and stand due to the aging of the knee joint, based on the principle of mechanical connecting rod, the CROE software is used to complete the three-dimensional model design of a new type of aging-assisting mechanism, and obtain the finite element analysis of the mechanical device in the horizontal state and the lifting state. The results show that the maximum deformation of the lifting plate does not meet the working requirements. The thickness of the lifting plate and the depth of the side hole are taken as the variables to explore the relationship curve of the maximum stress and maximum displacement. Finally, the minimum device quality is taken as the optimization goal to obtain the design parameters with the maximum deformation less than or equal to 0.1 mm. In this way, a new type of aging assistance mechanism is designed to meet the needs of the elderly.