A numerical analysis model for computing the temperature field of the tank power compartment armored plate was set up. The infrared radiation feature of the tank power compartment armored plate was calculated in theory. Solid wall surface temperature field was computed by adopting coupling calculation method, coupling heat transfer between armored plate and air was computed and effect of sun irradiation on board temperature field was considered. Then, temperature field distribution and radiation spectrum intensity distribution were forecasted. The relative error of the calculating values is less than 9.034%, which can basically meet the requirements of engineering applications. The study result indicates that the top board of power compartment is the mainly source of radiation. Exhaust shutter and top armored plate near exhaust pipe are the evident region of IR radiation character of tank.