Abstract: In this paper, the fatigue assessment of welded joints in thin plates was conducted using zero-point effective notch stress. This method comprehensively considered the influence of overall structural stress and the nonlinear stress peak at the root of the notch to the zero-point position. Based on the critical distance method and zero-point structural stress method, the zero-point stress position was taken as the critical distance for the fatigue assessment of welded structures. Through fitting the fatigue test results of two different types of welded joint specimens (T-type single-sided welded joint and lapped joint with different thickness combinations), it was found that there were significant differences in the zero-point effective notch stress when evaluating specimens with different cross-sectional stress linearization at the weld root. Among them, the width of the scattered band of the S-N curves obtained by linearizing the stress at the weld toe cross-section was the smallest. Furthermore, the difference of scattered bands between the S-N curves of considering for weld toe and weld root failure simultaneously and separately was not significant, proving that this method could be used simultaneously for fatigue assessment of both weld toe and weld root in welded joints.