Cloud contamination may affect the simulation of the radiation of a cloud area and hence results in the discard of a large number of satellite data. According to the current application of the Community Radiative Transfer Model (CRTM) and the principle of infrared remote sensing, the radiation transfer module in the CRTM is modified and a CRTM cloud mode which can simulate the infrared radiation of cloud areas is proposed. The CRTM cloud mode is used to simulate the channel brightness temperature of the Atmospheric Infrared Sounder (AIRS). The sensitivity of the new parameters added to the cloud mode is analyzed. The results show that with the decline of channel altitude, the atmosphere which contributes greatly to the radiation received by the satellite decline too. The altitude where the large deviation area locates is becoming lower and lower. In the large deviation area, the deviation increases with the increasing of cloud amount. When the sky is fully covered by cloud, the deviation reaches its maximum. When cloud amount becomes larger, the vertical variation of the temperature profile inputted may cause the radiation emitted by cloud top to form the same vertical distribution. This is in accordance with the vertical variation occurred when the brightness temperature simulated by the CRTM cloud mode increases with the rising of cloud top. The brightness temperature value simulated by the CRTM cloud mode is more sensitive to the newly added parameters of cloud amount and cloud top altitude. This accords with the law of atmospheric infrared radiation transfer.