The perfect theoretical calculation models of the satellite’s temperature field and infrared feature are established. First, according to the space locations of the satellite, the earth and the sun, the space heat flux that the satellite gets is calculated. Second, the surface temperature distribution of the satellite is got by solving the transient heat balance equations with the use of the Finite Element Method (FEM). And on the basis of the solved surface temperature distribution, taking the satellite as a point object, the spatial distribution of infrared radiation intensities in two IR bands is calculated. Finally, infrared radiation intensities in two IR bands of the satellite, the satellite’s body and solar panels are compared. The influence on the satellite’s infrared feature of the spatial heat flux is analyzed in detail. The research results have referential value on infrared detecting and recognition of spatial targets.