The damage tolerance analysis of wing external store mounting pylon structure is an important content to ensure the safety of structure and achieve the expected target mission. At present, nobody cares to make inquires about the damage tolerance analysis and research on the UAV wing external store mounting pylon. Taking a highaspectratio UAV wing combined probe pylon as an example, the damage tolerance analysis of the wing external store mounting pylon is made. According to the structural design features of wing combined probe pylon, a finite element analysis model of pylon is established, and the fatigue analysis dangerous points are determined by stress analysis of fatigue load conditions. And the random spectrum compilation method is adopted to obtain the damage tolerance load spectrum of the analyzed part. Based on the fracture mechanics, the RungeKutta method is used to estimate the crack propagation behavior, obtaining the crack growth characteristics and curve of the analyzed part. The analysis results show that the crack propagation life of the analyzed part of the pylon is 11,615,250 flight cycles, meeting the expected design requirements of residual strength value. And the inspection interval can be determined according to the crack propagation life.