Abstract: To improve the service reliability of the welded structure of a certain type of centrifugal aluminum alloy fan impeller,the critical length of the bead was checked based on the working load of the fan impeller. The differences in welding residual stresses produced by different welding procedure specification and their effects on the bearing capacity of the welded structure were analyzed by finite element simulation calculations. Comparing different welding procedure specification,qualitative analysis of negative influence of hot crack of bead and incomplete penetration of weld root on the bearing of the component,and a welding procedure specification with relatively small loss of the bearing capacity of the component was selected. The superposition effect of welding residual stress and working load in two-way welding was weaker than one-way welding,so it was more conducive to structural load bearing. Incomplete penetration of weld root in the inner bead were more favorable for loading than that in the outer bead. Hot cracks of weld bead in the outer bead weakened the structural load-bearing capacity less than that in the inner bead. Considering the influence of welding residual stress and welding defects on the bearing capacity of components,a more reliable welding process specification was given.