The imaging characteristic of background in elliptical orbit infrared platform is the basis of infrared image data processing. Firstly, the geometric projection model and signal transfer model of elliptical orbit infrared platform were established, and the imaging model of infrared sensor was given. Secondly, the effect of platform attitude, relative movement of background ontology and orbit on imaging characteristic of background were analyzed and the mathematical influence model was deducted. Finally, simulation experiments verified the correctness of the model, and the synthetic simulation results of imaging characteristics of background were given. The analysis results show that new features of background are presented in the detect image of infrared surveillance platform running on the elliptical orbit, and new requirements for infrared imaging data process are requested.