The surface structure of camouflage screen is mostly complex, and modeling calculation has high requirements for computing power. Surface structure disturbs the flow field around to influence the convection heat transfer and affects the surface temperature of the camouflage. In this paper, porous medium parameters of different values were attempted to ensure it had the same effect on the surface to get the simplification from the camouflage screen surface model to the porous medium model. Local modeling was established to analyze the influence of three typical camouflage screen surface structure on flow field around and its temperature field so that the corresponding porous medium wss found. The results show that this simplified method can greatly reduce the computational cost. This method can simulate the surface temperature of camouflage screen with large suface to evaluate the camouflage effect. The simplified model is used for outdoor bungalow situation. The infrared characteristics of outdoor bungalows and the ambient are simulated under natural conditions and the situation added and without camouflage simplified model respectively to analyze camouflage effect in day and night.