Target detection based on hyperspectral radiance images can improve data processing efficiency to meet the requirements of real-time processing. However, the spectral radiance acquired by the remote sensor will be affected by the atmosphere. In the present paper, hyperspectral imaging process is simulated to analyze the effects of the changes in atmospheric state on target detection in hyperspectral radiance image. The results show that hyperspectral radiance image can be directly used for target detection, different atmospheric states have little impacts on the RXD detection, whereas the MF detection is dependent on the accuracy of the input spectrum, and good results can only be obtained by the MF detector when the atmospheric states are similar between the radiance spectrum of the target to be detected and the simulated hyperspectral image.