Abstract: In order to improve the fidelity of the IR hyperspectral target characteristic simulation, an influence model was presented in this paper to calculate the influence of the nearby building on the target final radiation at certain wavelength. A virtual experiment scene was constructed with 1976 U.S. standard atmosphere. Simulation experiments were done based on the constructed virtual scene in 3.0-5.0m at intervals of 0.01m, and the calculation results were compared with the target reflected solar radiation and the target self-radiation. Experiments results show that the radiation influence from the building are higher than the target reflected solar radiation or the target self-radiation at some waveband ranges, which means the radiation influence is the most critical radiation in some images of the image cube. It proves the influence model presented in this paper is necessary and important in hyperspectral simulation. Through the analysis of simulation results, the building surface temperature, atmosphere transmittance and the valid radiation area are determined to be the 3 key factors to affect the influence radiation of nearby building.