The theoretical model to calculate the thermal IR radiative characteristics of different background,based on a system of energy equation,is established.By using the temperature-moisture coupling theory,the van at ions of the thermal and radiative characteristics of the natural background with the moisture are considered.Simulated radiative diurnal average surface temperatures of different background in the same environmental condition are compared with each other.The results show that there is some difference between IR radiative characteristics of different background.In daytime,the difference between natural and artificial surfaces is relatively distinct.