To solve the problems of the existing HPM radiation field power density measurement system, such as many measurement links, system complexity and long cable which can’t adapt to complex electromagnetic environment measurement, a miniaturized and integrated power density measurement system of high-power microwave radiation field is developed. An antenna-coupler-adapter is used as the front receiver, the back end of the system is a coaxial signal processing unit, where the attenuation, power detection and electro-optical conversion are achieved in the shield box, hence, the system can be measured and monitored remotely. Meanwhile, modular calibration is applied in the system, which can effectively reduce the measurement uncertainty. The system has 30 dB dynamics, a minimum measurable pulse width of 50 ns and a measurable radiation field power density of 100 MW/m². It is compact, easy to carry, anti-electromagnetic radiation, and capable of quick power density measurement of GW high-power microwave radiation field in X-band.