Abstract: Infrared radiant planar source is used to simulate certain infrared characteristic target, widely used in different infrared detection, controlling and guiding equipment's outer field test. The performance of infrared radiant planar source basically depends on its temperature field control. The structure and main parts of radiant planar source were described. Taper shape was adopted at planar surface to increase the infrared emissivity. High power heater controlled by temperature controller was used for heating. The heating power was determined by thermal analysis and calculation. The air duct was designed and suitable cooling fans were selected through CFD simulation. The experiment results show that the temperature stability and uniformity of whole radiant plane fulfill the requirement. The radiant source can be adjusted at any temperature in a range of 80 ℃,300 ℃ within 30 min. The temperature deviation is less than 1.5 ℃. The radiant source can simulate different infrared behaviors by setting different work temperature.