In response to the demand for infrared remote sensing of trace leakage of sulfur hexafluoride gas in power confined space and the lack of measured data in different scenarios and different environmental parameters required for the high-precision identification algorithm modeling of sulfur hexafluoride infrared spectra, the simulation of sulfur hexafluoride infrared spectra in confined space has been conducted. On the one hand, an infrared radiation transmission model of sulfur hexafluoride was established, and the influences of background radiation, atmospheric interference radiation and background temperature difference on the infrared signal of sulfur hexafluoride were analyzed theoretically. On the other hand, in order to solve the problem of insufficient on-site acquisition or measurement conditions for background radiation in some confined space scenarios, a laboratory detection device for sulfur hexafluoride infrared radiation simulation transmission was built, which not only helped to realize the background radiation simulations in different confined spaces by controlling and adjusting influencing factors, but also to validate the infrared spectra simulation results. The infrared spectra of sulfur hexafluoride under two typical backgrounds (cement wall and equipment metal shell) of confined spaces were experimentally simulated and collected at different temperatures, and at the same time, the infrared spectra under different atmospheric interference and sulfur hexafluoride concentrations were also simulated. As a verification, the whole transmission process of sulfur hexafluoride infrared radiation in a confined space was simulated, and the measured spectra were obtained and compared with the simulated spectra. The comparison results showed that the simulation brightness error was0.11-0.45 K, which preliminarily verified the feasibility of the proposed method, and provided a reference for constructing and improving the infrared identification algorithm of sulfur hexafluoride gas leakage in confined space in the future.