Considering the aircraft and its external components are subjected to complex and vari-able aerodynamic loads during the working process, the missile-frame clearance system of the air-borne external missile is investigated. The random vibration characteristics of the airborne external components are analyzed by finite element method. The finite element model is optimized with ref-erence to the test results, and the effects of different clearance on the dynamic response of the missile-frame system are compared. The result shows that the frequency response curves of the same position and the resonant peak frequencies are consistent under different clearances. The accelera-tion response at both ends of the missile is large and the amplitude near the center of mass is gentle. The results can be used to predict reasonable missile-frame clearance and make guidance to the structural design and reliability analysis of the missile-frame system.