Abstract: In this paper, material, loading type, misplacement, residual stress and short crack in notch root on fatigue strength of misplaced plate joints are considered separately. Based on the Peterson type formula and the Topper type formula, two formule of effective stress concentration factor are developed. As an example of application of the method, these formule of effective stress concentration factor are estimated. Good agreement between the estimation and experiments is achieved. This method has referenced value for engineering application.