Abstract: In order to analyze the common corrosion hole defects in the inner wall of pipeline more accurately, a three-dimensional conical model was used to simulate the corrosion hole defects and a conical defect analytic method of pipeline internal detection based on magnetic flux leakage (MFL) was proposed. The analytic model of conical defect was established by using magnetic charge as the link and the analytic expression of magnetic leakage field at the defect was obtained. The influence of defect depth and radius on defect MFL signal was analyzed and the theoretical calculation results were verified by finite element simulation. The results show that calculation results based on cone defect analytic model had rather better consistency with magnetic flux leakage field distribution of cone defect by simulation analysis. The amplitudes of magnetic flux leakage signals were positively related to cone defect depths, negatively related to cone defect radius and lift-off values. The model can effectively describe magnetic flux leakage distribution of the pipeline internal corrosion holes and provide a new idea for solving pipeline magnetic flux leakage internal detection.