Abstract: Objective The aim is to calculate welding residual stresses of storage tank structure and predict weak position. Methods Through mechanical properties test, material property parameter library of 2219 aluminum alloy is constructed. Finite element model of stir friction butt welding is established by finite element method of thermo-mechanical coupling. And through welding test, welding thermal cycle curve and residual stress are calibrated to obtain welding heat source model parameters that can accurately reflect distribution characteristics of temperature field and stress field. Further, the model is used to simulate welding residual stress of storage tank structure. Results The results show that the calculated results and the measured curve of welding thermal cycle curve match better, the error between the calculated results and the measured results of welding residual stress is less than 15%. Simulation results of welding process of storage tank structure shows that the maximum value of welding residual stress in main part of storage tank is 265 MPa. Conclusion Through the test, appropriate welding parameters of 2219 aluminum alloy with different plate thickness is obtained. Numerical simulation shows that the stress in γ-ring weld and bottom ring weld of storage tank structure is large, among which hoop stress accounts for a relatively large percentage. The weak position is at γ-ring weld and bottom ring weld.