漏磁检测技术在铁磁性材料缺陷检测领域中得到了广泛应用，其中磁偶极子法是目前应用最广泛的从结构缺陷中预测漏磁的数学方法。磁偶极子法多用于规则缺陷的漏磁信号预测，对于复杂缺陷，已有的单元磁偶极带叠加模型可以预测其漏磁信号，但是由于模型计算所需的复杂缺陷磁荷密度未知，且其分布不均匀，计算复杂。因此，提出了离散化磁荷密度场的计算方法，该方法可以快速计算三维不规则缺陷的磁荷密度，结合单元磁偶极带叠加模型直接进行漏磁信号预测，以降低计算复杂度，迅速而准确地获取三维不规则缺陷的漏磁信号。将该方法用于单元磁偶极带叠加模型得到的预测信号与COMSOL软件仿真信号比较，表明该方法是可行的。验证实验结果表明，使用该方法的单元磁偶极带叠加模型相比于原模型预测性能明显提升，预测误差最大减少90.08%，计算时间减少97.43%，为三维不规则缺陷的磁荷分布计算提供了快速有效的解决办法。

The magnetic flux leakage detection technology has been widely used in the field of ferromagnetic material defect detection, in which the magnetic dipole method is currently the most widely used mathematical method for predicting magnetic flux leakage from structural defects. The magnetic dipole method is primarily employed for predicting the magnetic flux leakage signal of regular defects. The unit magnetic dipole band superposition model can be used to predict the magnetic flux leakage signal of complex defects. The magnetic charge density of complex defects needs to be calculated when the model is used for prediction. However, the magnetic charge density distribution of complex defects is inhomogeneous, and the calculation is complex. Therefore, a calculation method of discrete magnetic charge density field was proposed for calculating the magnetic charge density of three-dimensional irregular defects. The computational complexity of the model was reduced by using this method and the magnetic flux leakage signal of three-dimensional irregular defects can be quickly and exactly obtained. Comparison between the signal predicted by the unit magnetic dipole band superposition model based on discrete magnetic charge density field and the signal simulated by COMSOL software demonstrates the feasibility of the method. Experimental results show that the prediction performance of the model has been significantly improved by using this method, the maximum prediction error is reduced by 90.08%, and the calculation time is reduced by 97.43%, thus a fast and effective solution for the calculation of the magnetic charge distribution of three-dimensional irregular defects is provided.