The infrared radiometer is generally used for the calibration of the infrared thermal imager testing equipment. A measurement module and method for infrared radiometer were introduced. A measurement scheme of sample and hold was designed, the sampling pulse was generated from the reference signal, and the sampling point was set at the 1/4 phase of each signal period, which could significantly improve the measurement ability of weak signals. For the black-body radiation signal at 35 ℃, the measured signal strength could be increased by 57.6% by comparing with the existing scheme. Under the condition that the background temperature of the infrared thermal imager testing equipment was 22 ℃, the measurement signal accuracy could be improved by more than 50% through the comparison test with the existing instruments.