To achieve effective detection of hypersonic aircraft, radar needs to emit high-power signals to overcome signal attenuation caused by high-speed flight of the aircraft. This long-term high-power operation will cause the electronic components in the radar transmission component to accumulate heat due to the high power load, resulting in a decrease in antenna gain and the radar"s ability to receive target echo signals, leading to deviations in the echo intensity test results. A phased array based radar echo intensity testing technology for hypersonic aircraft has been proposed to address this issue. By combining a high stable frequency source to generate frequency and orthogonal phase demodulation processed orthogonal reference signals, the original radar echo signal is reconstructed through phase demodulation reversibility. Design phased array radar system structure, suppress interference through beamforming and space-time adaptive processing, efficiently track and detect targets using single beam phased array technology, and achieve beam flexible electronic scanning based on new beamforming methods. Establish light intensity correlation verification and calibration of echo intensity, calibrate the characteristic parameters of each unit, overcome the problem of antenna gain decrease caused by heat accumulation, and ensure the accuracy and reliability of echo intensity testing. According to the experimental results, the four point coordinates of the radar cross section of this technology are (-200m, 150m), (-300m, -300m), (300m, 300m), and (200m, 150m), respectively. When the azimuth is 0, the maximum amplitude of the echo signal is 0dB, the maximum phase of the echo signal is 150 °, and the minimum is 30 °. The obtained results are consistent with the experimental indicators and have good testing effects.