云是造成空中目标探测和识别困难的重要因素。从目标和云的红外辐射出发，分析了云影响目标红外探测的问题。首先根据目标和云的4种位置关系，建立了不同情况下探测器接收到的目标和云背景辐射差的计算模型，然后对模型中参数的计算进行了讨论，最后根据模型进行了实例的仿真计算和分析。计算结果表明：在8~14 μm波段上，目标与背景的辐射差在9 μm波长、50°方向角附近的值比较大，而在波长较长、方向角角度较大的部分值较小。该结论可以为红外探测系统的设计提供依据。

Cloud is an important factor for the difficulty in air target detection and recognition. Based on the IR radiation of target and cloud, the effects of cloud on the target IR detection were analyzed. Firstly, according to the 4 different position relationships of target and cloud, the models for calculating the radiation difference of target and cloud that received by the detector were established, and then the calculations of the parameters in the model were discussed. Lastly, the simulation calculation was done as an example based on the model, and the results were analyzed. The results show that：in the band of 8-14 μm, the radiation difference of target and cloud has bigger value near the wavelength of 9 μm and direction angle of 50°, and smaller value appears at the longer wavelength and larger direction angle. The conclusion can provide the basis for the design of IR detection system.