Abstract: Aiming at the problem that the mass of jaw crusher is generally heavy at present. The object of study is movable jaw. According to the static analysis, topology optimization, mechanical characteristics and working requirements of movable jaw, the primary selection of design variables for the improvement of movable jaw structure is completed. And according to the sensitivity analysis, the optimal design variables of two lightweight structural improvement schemes are proposed. In the optimization design module of ANSYS Workbench software, an optimization model with the minimum mass of movable jaw as the design objective and the fourth strength theory as the constraint condition is established. The strength, deformation and mass decrease effects of the two improved schemes were compared and analyzed. The results show that scheme one has better lightweight effect, and the mass of movable jaw is reduced by 6.15% on the basis of satisfying mechanical properties, which provides theoretical guidance for the further research on lightweight design ofmovable jaw .