In order to solve the problem of frequent cracking of a stability augme ntation structure of a transport aircraft fuselage tail, the method based on finite element modal analysis theory of random vibration response calculation is pr oposed. By reverse engineering, the stability augmentation structure is excited with the vibration spectrum of flight through the way of pseudo excitation, and the random vibration response of the stability augmentation structure is acquired. According to calculated result and theoretical analysis of the flight testing vibration data, the fracture and crack formation of the stability augmentation structure is able to be basically determined as emerging close to the resonance condition in flight course. On resonance condition, cracks are propagated on the root of stability augmentation structure, the theory analysis results and computed data are provided as theoretic reference and data support for the stability augmentation structure subsequent improvement and optimal design.