Abstract: In order to solve the problems of poor universal and miscellaneous types of existing various self-propelled gun turret assembling platforms, a variable diameter turret assembling platform was designed based on the analysis of their size requirements. To realize a lightweight design and improve the stiffness and strength of the platform, a method of target interaction optimization design based on topology optimization and size optimization was proposed. Firstly, setting the minimum quality of the tray, causing the platform damaged easily, as the optimal target, the maximum allowable displacement and the allowable stress as constraint conditions, the cell density as design variables, the topology optimization of the tray was carried out. Then the topology optimization results were regularized, and setting the improvement of stiffness and strength as the optimization target, no increasing quality as constraint conditions, the important size parameters as design variables, the size optimization of the tray was implemented. The results show that, the quality can be reduced from 1 421 kg to 1 032 kg after optimization, the structural stiffness and strength are greatly improved. The effectiveness of the optimized results is verified by tooling test.