Abstract: In order to sim ulate the airflow and heattransfer in a space station cabin,num erical analyses of heat transfer and ventilation in a com plicated cabin under m icro gravity environm entare carried outin w hich cases w ith slotair inletatthe top corners andoutletin thebottom corners arediscussed. Fourrepresentative casesw hich are em pty cabinand cabins w ith adiabatic/isotherm alobstacles are studied. The num ericalresults ofheattransfer and ventilation under various m odel scales in each configuration are elucidated. The research enunciates that shot inlet is m ore effective to suppress natural convection. Even for com plicated configuration problem s, naturalconvection can be dram atically de pressed w hen the m odelsize is properly reduced. How everthe concrete m odelsize com pa ratively depends on the given configuration. As far as the slot inlet ofventilation is con cerned, the appropriate m odelscale can be chosen as 1v5 in engineering applications.