Based on the requirements of photoelectric equipment chassis module lock body loads and boundary conditions, according to the minimum weight principle on the lock body and the actual operation conditions, relative parameters of the lock body are optimum simulated. The relevant parameters setting of the block body is given by UG NX7.0 finite element software. The weights and the driving dimension of sketch drawings are iteratively calculated by the software. The results trend to convergence. And the minimum weight of a block body is got on the condition of certain strength and stiffness. The requirement of equipment weight loss is met through analysis and calculation and the optimized design reference are provided to system and other parts.