Abstract: The radiated power measuring system mainly consists of receiving antenna, attenuator, microwave detector and waveform recorder. How to effectively suppress the influence of changes in microwave detector characteristics on pulse microwave power measurement is the key to improving the accuracy of outdoor HPM power measurement. The principle of using the Comparison method to measure the power of pulsed microwaves is to sequentially output two video pulses from the tested pulsed microwaves and a known power reference pulsed microwaves through the detector. Measure the amplitude of these two video pulses, and the power of the tested pulse microwave is equal to the ratio of the video pulse amplitude corresponding to the tested pulse microwave to the video pulse amplitude corresponding to the reference pulse microwave, multiplied by the known reference pulse microwave power value. Under the condition that the tested pulse microwave signal and the reference pulse microwave signal are in the voltage power linear range of the microwave detector, in theory, the comparison method for measuring pulse microwave power is not affected by the temperature characteristics of the detector. Comparison method has potential appliance value in achieving accurate measurement of HPM radiated field power in environments with significant temperature changes.