The work aims to carry out space optimization research on the sanitary area of China's new generation manned spacecraft, explore functional space optimization design methods, improve space utilization efficiency of manned spacecraft, and enhance astronauts' comfort experience. Based on the function and structure of the sanitary area of China's space Station, the composition of the functional components of the sanitary area of China's new generation manned spacecraft was discussed. The initial concept on space layout of the sanitary area was established based on astronauts' movements and gestures in microgravity. Based on the analysis of the bulkhead layout of the sanitary area, the astronauts' field of vision and the optimal operating space under microgravity, the modeling of relevant functional components was carried out. JACK software was used to conduct simulation analysis and evaluation based on the man-machine interaction node of the sanitary area. The design scheme was improved based on the evaluation results, and the space optimization of the health area was completed through the envelope generated by tracking the astronauts' activity trajectory. The effectiveness and reliability of the functional space optimization design method were verified by comparing the comfort, maneuverability and space size of the design scheme before and after the optimization of the sanitary area of China's new generation manned spacecraft, which provides a reference for the comfort and integrated design of manned spacecraft.