Abstract: To address the issues of structure symmetry and symmetrical precision improvement caused by the machining of multi-specification symmetric workpieces, a symmetrical optimization method for machine tool accuracy with asymmetric structures and multi-stroke working conditions is proposed. The rocker arm welding machine is taken as the research object. By constructing optimization objectives for the deformations of the workpiece positioning surfaces and the corresponding deformation differences of the positioning surfaces, multi-objective optimization is carried out to improve the precision symmetry and precision class of the whole machine. The optimization results show that the deformations of the positioning surfaces of each stroke of the rocker arm welding machine are reduced by more than 26.2%, and the differences in deformations of the positioning surfaces are reduced by more than 47.9%. The form and position errors of each positioning surface are improved, with verticality tolerances enhanced by 2 grades, inclination tolerances by 1 grade, and concentricity tolerances by 1 grade. This indicates that the proposed symmetrical optimization method for machine tools with asymmetric structures and multi-stroke working conditions has high rationality and effectiveness, providing reference value for the optimization design of machine tools.