Abstract: As manned space technology develops, manned spacecrafts are developed from single cabin to combination of several cabins in orbit. The air environment of manned spacecraft combination is usually controlled by one or several cabins with support of inter-cabin ventilation. In this paper, a calculating model of CO2 partial pressure control system of manned spacecraft combination has been developed with the interdisciplinary tool of Ecosimpro. Using this simulation model, CO2 partial pressure of every cabin has been analyzed during the assembling process. According to the results, when the number of cabins is up to three, CO2 partial pressure of cabins without CO2 control system is beyond the upper limit. Three control strategies are proposed to optimize CO2 partial pressure, among which the first one is increasing intercabin ventilation flux, the second one is varying location of CO2 partial pressure control system, and the third one is the collection of the two forementioned ones. Simulation has been carried out for the three strategies, which testifies the third strategies is the most effective one.