The fatigue load of an aircraft plays a very important role in determining the service life of the aircraft. A method of calculating aircraft fatigue load is given in this paper, which is applied to a certain type of aircraft and effective in practice. The fatigue load finally used for designing is achieved first by integrating the numerical value simulation results or the pressure measuring test results to obtain the load distribution over and the acting point of load on each part of an aircraft body, and then performing load balance correction according to the equation of motion balance of aircraft.