Three dimensional steady numerical simulations are conducted to simulate the thermal and moisture environment in a refuge chamber by using a commercial computational fluid dynamics (CFD) software Fluent, and the distribution characters of temperature and relative humidity fields in the chamber are obtained. The simulation results show that the temperature and relative humidity can basically meet the design standard. However, the distribution gradient of temperature and relative humidity is very large and the relative humidity is quite low. The supply air inlet 1 just has a limited effect on the airflow distribution in refugee chamber. There is a large turbulence zone on the height level of human head, where has a bad air quality. To solve the problems, an improved air distribution plan is presented, which modifies the locations of air distributors and the supply air parameters. The simulation results show that a more uniform distribution of the temperature and relative humidity can be obtained if the improved air distribution plan is applied, and an average temperature of about 303 K and a relative humidity of about 55% can be achieved.