The invention discloses a deformation active phased array radar detection performance rapid assessment method based on electromechanical coupling. The method comprises the following steps: 1) determining an array antenna array element type of an active phased array radar; 2) determining a structure parameter and an electromagnetic working parameter of an array antenna; 3) computing an ideal antenna directional diagram and an antenna important performance parameter based on the array antenna radiation principle; 4) performing structure analysis on a radar antenna under certain working environment load; 5) obtaining array antenna unit structure displacement; and 6) rapidly determining the radar main detection performance index after deformation according to a radar main detection performanceanalysis parameter model before and after antenna structure deformation. Through the method disclosed by the invention, the rapid prediction and analysis method of the radar detection performance ofthe radar under the environment load effect after the antenna array structure deformation is realized.