To address the issue of fatigue crack propagation in the welded structures of rocket storage tanks，a rapid prediction method for the structural fatigue life based on the Kriging model is proposed.A scaled finite element model is established for such a tank，and joint simulations with the ABAQUS and FRANC3D software are conducted to study the crack propagation behavior of the initial cracks under different regions，stress ratios，and inclination angles.The results show that the crack propagation rate in the weld zone is higher than those in the heat-affected zone and base material zone.The crack propagation rate in the longitudinal weld zone is higher than that in the circumferential weld zone.The crack propagation rate in the longitudinal weld zone increases as the stress ratio decreases，and the fatigue life is the longest when the initial inclination angle is 0°.A high-accuracy Kriging model is developed，taking the initial crack location in the longitudinal weld zone，the inclination angle，and the stress ratio as the inputs and the fatigue crack propagation life as the output.The model enables rapid prediction for the crack propagation life in the welded structure of a storage tank.The results show that compared with the extended finite element method，the proposed method can shorten the life prediction time by more than 10 times while ensuring low calculation errors.