Abstract: Magnetic dipole theory is one of the successful models for explaining the defect leakage magnetic fields.The complex shapes of defects are directly influencing the magnetic flux leakage signals,however,the defect is often simplified as a rectangular or a circular notch in the researches at present.The analytical expressions of the magnetic flux leakage signals for ladder notch are given in this paper firstly.The rectangle type,V type and combinational type notches can be regarded as the transformation and combination of ladder notch,then,their analytical expressions of the magnetic flux leakage signals are obtained.In this paper,the analytical expressions for rectangular notch agree well with the results of previous literatures,the analytical expressions for ladder type and combinational type notches are obtained for the first time,and the analytical expressions for V type notch are of a certain difference to the existing literature.The correctness of the expressions is verified by the comparisons of the present analytical expressions and the numerical integral results.