Abstract: Using experimental and finite element analysis methods, the effects of electrode forging force are investigated on residual stress and fatigue behavior of spot welded aluminum alloy joints. Results show that forging force significantly reduces the residual stresses in the heat affected zone (HAZ); the fatigue cracks no longer initiate from the HAZ, while all cracks begin from the edge of nuggets. The mitigation of residual stress decreases the driving force for crack propagation, and leads to higher fatigue strength.