Abstract: KM6 manned test chamber is developed for the Chinese manned space environment testing in a simulated space environment. The design for the manned test chamber is introduced in the paper, and the design is optimized with the method of finite element calculation. The final chamber structure and the results of the finite element optimizing calculation is afforded. The ultimate pressure in the chamber reached 5 2×10 -4 Pa. The design of the test chamber meets the demands for structure design.