Abstract: According to the importance of the CO2 open loop cycle refrigeration applied to the rescue cabin, the refuge chamber and other limited airtight space, th e FLOWMASTER simulation software of the thermal fluid system was applied to design the simulation system of the CO2 open loop cycle refrigeration applied to a limit ed airtight space.Under the conditions to meet the designed refrigeration value and the pressure drop and temperature drop at the inlet and outlet of the pneumatic blo wer, the tube length of the evaporator was optimized and the optimum length of the evaporator was obtained.Meanwhile the refrigeration system features and the differe nt refrigeration value under the non designed performances were checked.The test certification was conducted on the refrigeration simulation system. The simulated val ue and the test value were well fttd and the simulation accuracy and precision of the system were verified.