Abstract: Based on the finite element method, the bearing capacity and deformation resistance of the structure are analysed. Then, the stress tensor of the structural element node is extracted, and the fatigue life of the cold end bolt connection structure of an aero-engine under complex external load is predicted by stress combination transformation and two kinds of stress (Goodman and FKM) correction methods, which is based on the rain flow analysis method and miner criterion cumulative damage. The results show that the fatigue life of the material can be increased by 5.8% and the statistical cycle of life can be increased by 4.5×10⁵ (Times) through the reasonable selection of bolt preload. There is an optimal preload, which can provide an effective means for the robust design of aeroengine connection structure. Compared with Goodman's method, FKM method has a better safety margin with a statistical decrease of 0.6% in the cycle number of the best fatigue life.