Based on the finite element theory and topology optimization method,taking the cantilever beam of a space launch tower crane as the research object and aiming at the quality control of stiffness value, the quality of the cantilever beam was optimized through theoretical modeling,static calculation and topology calculation,and the optimal structural form was determined through comparative analysis.The results show that the optimized structural performance and economic performance meet the engineering requirements.At present,the design has been successfully applied in engineering practice.