The simulation means of the target surface radiation equilibrium temperature field, in real-time infrared imaging simulation founded to supply high quality infrared image to evaluate IR detection image processing system in laboratory, is issued. For the target models based on the finite difference theory the lumped parameter thermal analysis means is adopted to make targets and environments dispersed-to several nodes with thermal capacitance property, which describe thermal system transient processing. The three modes in the thermal system, heat fulx, convection, radiation are abstracted to heat-resistance connected with every node, which reflects heat-exchange ability, so the heat flux description for the whole target infrared radiation and the equilibrium temperature field for the surface radiation are obtained. Infrared imaging simulation system based on professional thermal analysis software Sinda/G with the advantage of the thermal analysis means by adopting lumped parameter also works in the finite element post treatment after processor software femap's figure demonstration function. The color of nodes renders temperature results, and uses the nephogram and cartoon technology to display steady and transient temperature distribution conveniently to achieve the target infrared imaging simulation.