Simulations on three kinds of working conditions (heating, cooling and radiation) and different kinds of air-inlet and air-outlet patterns to gain the corresponding distribution of air velocity and temperature inside the shelter were done with FLUENT software. The results indicated that: the cabin average temperature rose from 243 K to 290 K after 300 s when heated; the temperature reduced from 343 K to 302 K after 300 s when cooling; the temperature reduced from 343 K to 302 K after 264 s when considering the effect of radiation during the course of cooling. The results also indicated that: the average air velocity of left-in and left-out pattern was the biggest in the upper space of shelter, while it was the biggest in the lower space of shelter by choosing the right-in and right-out pattern; ventilating effect of complicated air-inlet pattern was better than that of simple air-inlet pattern, and the front-direction removal pattern was better than the down-direction removal pattern. 