Abstract: Optimization design method of welded structure was put forward with welded joint fatigue damage as constraints.According to International Institute of Welding (IIW) standards and Miner cumulative damage theory, virtual fatigue test (VFT)was presented to predict the welded joint's fatigue accumulation damage. Approximation models based on design of experiments (DOE)were used to improve optimization efficiency.The anti-fatigue lightweight design of welded bogie frame was preformed using this method.According to UIC515-4, the maximum extraordinary stress and the three key welded joints fatigue damage are considered as constraints, the plate thickness as design variables and the minimum mass as the object function.Latin Hypercube method was used with 10 design variables to provide 120 sample points, and approximation models for bogie frame's strength and fatigue analysis are constructed using Kriging model.The optimization with sequential quadratic programming algorithm is performed on Kriging approximate model, and mass reduced by 11.6%.This method has some reference value to the anti-fatigue design of complex welded structure.