Because of the serious interference of cloud contamination with atmospheric infrared remote sensing, a large number of infrared data are abnegated. To make full use of the infrared data in assimilation to improve the initial field accuracy and numerical prediction effectiveness, a general Community Radiative Transfer Model (CRTM) is used to simulate the brightness temperature of channels of the Atmospheric Infrared Sounder (AIRS) and analyze the effect of cloud parameters (cloud type, cloud moisture, cloud thickness and cloud top) on the brightness temperature of channels of AIRS. The results show that 1) Infrared radiation can be truncated by clouds, so that only the atmosphere above cloud top can affect the radiation; 2) The brightness temperature decreases gradually with the increase of water content, but its decrease rate will slow down until it is constant. The particles with a larger effective radius have stronger scattering for the radiation, so the corresponding brightness temperature will be lower; 3) For a constant cloud top height, the variation of cloud thickness will not affect the brightness temperature. For a constant cloud bottom height, the thicker the cloud is, the lower the brightness temperature will be; 4) Since the brightness temperature of ground channels are more sensitive to the variation of cloud top height, the brightness temperature of the channels above cloud top will not be changed.