Infrared screen is an important IR camouflage equipment of ground objects. It is usually composed of heat insulation blanket and camouflage net. The physics model of heat transfer of infrared screen is established. Solar and sky radiation, radiation heat transfer, heat conduction and natural convection involved in above model are analyzed. Simulation analysis and calculation is performed to the process by finite element method. And the radiation temperature values of most outside surface of the infrared screen system are figured out. Then the target temperature and the heat insulation blanket and the camouflage net material parameters influencing on the temperature value are investigated. The established model and calculation results can provide references for the analysis of camouflage effect of infrared screen and relative engineering applications.