In view of the problem that the time taken in test calibration is longer which results in low efficiency in phase shifter of microwave landing system land equipment (MLE) fault diagnosis, based on the calibration principium of phase array antenna, scanning antenna array parameter obtaining method and phase shifter fault diagnosis flow are analyzed. Optimum phase for every antenna array is calculated with phase-only shaping of amplitude pattern algorithm, which modulates factors of close equation with measuring radiation power and calculates the optimum phase with former quantization error added in, so that array parameters are calculated through a small quantity of iteration, and calibration time is shortened. Consequently, phase shifter fault is diagnosed quickly with array parameters after test calibration compared with the array parameters deposited in RAM of antenna controller after task calibration. Finally, the feasibility of this method is verified through computing simulation.