The intensity of background radiation directly determines the sensitivity limit of the infrared telescope system and directly affects the system design. Background radiation is also an important index to reflect the astronomical observing conditions and performance of observatory stations. The atmospheric infrared background radiation of Ali, Delingha Observatory and Huairou Observatory astronomical observatories were measured, particularly the first-hand data of atmospheric infrared background radiation were obtained for the Ali astronomical observatories. The measured results show that the atmospheric infrared background radiation intensity and the diurnal variation of the radiance on the Ali astronomical observatories are the smallest among the three stations, and the average values of the highest radiance is 1.30×10-6 W·cm-2·sr-1. The maximum diurnal variation of Ali′s radiance mean value is only 18%. Therefore, the lowest infrared background radiation limits is Ali astronomical observatories. The second is Delingha Observatory. Finally, the measured radiance in sky sweeping was compared with the MODTRAN software simulated radiance. It is found that there is quite a difference between the simulation results and the actual measurement in the high altitude areas of the Qinghai-Tibet Plateau, whether it is the standard atmospheric mode or the actual atmospheric mode.