Based on the requirements of airworthiness authorities and aircraft manufacturers, this paper explains the reason why the number of passengers needs to be reduced when the cabin exit door fails. According to the requirements of FAA, EASA and CAAC for cabin exit door inoperation, this paper compares and analyzes the requirement of different aviation authorities, and provides the calculation method of passenger reduction. When the door fails to reduce the number of passengers, airlines need to consider whether the flight is an overwater flight, exit door capacity and slide raft capacity. Based on actual cabin layout, combined with the flight sales situation, the economic loss caused by the failure of the passenger door is minimized while meeting the airworthiness requirements. By using calculation formula and calculation form, passenger reduction value and passenger reduction area can be obtained quickly. After analysis and calculation, FAA passenger reduction method is simple, but passenger reduction area appointing is strict and EASA passenger reduction method is complex, but passenger reduction area appointing is more flexible.