Based on the flow field and temperature field results calculated by CFD code and the environment data calculated by Modtran, the calculation model of the infrared radiation signature of aircraft under typical background was established. The factors of the wave band, season, emissivity and bidirectional reflectance distribution function were calculated. The calculation method was verified through a ground test data, and the calculation data is in good agreement with the experimental data. This model can provide a method and tool for more accurate analysis of aircraft′s infrared radiation signature and more reasonable evaluation of infrared suppression methods.