The structural stiffness and strength of chassis frames significantly impact the operational reliability and testing accuracy of mobile aero-engine test platforms. To ensure structural integrity under representative load conditions, a comprehensive finite element analysis (FEA) was conducted on a typical chassis of a mobile aero-engine test platform, focusing on front and rear axle torsion and static vertical load conditions. Key performance indicators, such as torsional stiffness, structural deformation and stress distribution, were evaluated quantitatively to demonstrate compliance with safety and stability requirements. Furthermore, parametric sensitivity analysis and response surface-based multi-objective optimization were employed to explore lightweight design possibilities. The optimization results showed a mass reduction of approximately 15%, achieving an optimal balance between structural weight and torsional stiffness. These results confirm the validity of the analytical and optimization approaches proposed, providing practical guidance and theoretical support for designing lightweight, high-performance chassis structures for mobile aero-engine testing applications.