Abstract: In order to overcome some shortcomings faced by defect positioning while using the traditional artificial circle taking defect block positioning in the field of pipeline magnetic flux leakage detection data, such as deviation and large circled range, this paper proposes to use the step coefficient and the combination boundary for the manual extraction of the mileage boundary of the defect block. A boundary search strategy with the distance and amplitude of the bilateral valley points, and a boundary search strategy based on the amplitude threshold method and the peak-to-valley differential threshold method for finding the channel boundary is proposed for the channel boundary. Finally, the comprehensive mileage boundary search strategy and Channel boundary search strategy, a boundary search method based on manual extraction of defective blocks is designed. This method will help to establish an effective magnetic flux defect feature database, extract the essential characteristics of defect data, improve the accuracy of defect extraction features to a certain extent, reduce time complexity, and provide data support for quantification of magnetic flux defects and decision basis.