In order to understand and master the fleet operational reliability status, civil aircraft manufacturer set an appropriate threshold for each type of aircraft fleet and compared with the actual value to quickly grasp the fleet alert status, which is the most basic reliability analysis mode in which the threshold value that is alert value. This paper describes the management methods of civil aircraft alert value, a detailed description of the alert value calculation, approval, amendments and final entry into force of the entire management process, and the alert value management method in ARJ21-700 aircraft flight test process was introduced.