Abstract: The fatigue test of a full-scale aircraft body aimed to understand the initiation and development of fatigue damage and fatigue crack of its critical structures, and hence to determine fatigue life, maintenance and repairing cycles of the aircraft. The work of nondestructive testing and acoustic emission (AE) monitoring during the whole fatigue test played a key role in guaranteeing the success of the test and in achieving the prescribed goal. The fatigue test of main landing gears under the load simulating the taking off and landing on conditions formed an essential part of this fatigue test. The main structures to be monitored were the beams and pivots. In order to obtain AE signals related with fatigue damages under interferences due to high impact and background noises, present authors used the combination of trend analysis, spatial filtering, time-based, amplitude-based and frequency-based filtering techniques, together with multi-parameter identifications, and realized the real time monitoring of the upper pivot damage during the fatigue test.