Numerical generation method of random surface was used to simulate the topography of satellite undulating surface. Considering the radiative flux of space environment, the surface temperature distribution was calculated through the energy equation, with the transfer coefficients determined by Monte-Carlo method. Undulating surface infrared characteristics were calculated and analyzed, through the model by the Torrance-Sparrow bidirectional reflectance distribution function, which is based on the common material and aluminized polyimide film. Simulation results show that infrared characteristic of the undulating surface is quite different from those of ideal plane surface. The surface temperature distribution and infrared characteristics are strong correlative with the surface topography, which provides the research of space infrared detection technology with more effective support.