通过应用电磁感应式杂质检测系统，对不同作用机理的材料进行杂质检测试验。研究了不同材料与线圈耦合度的关系，找出了提高检测灵敏度的方法。 Through the application of electromagnetic induction impurity detection system, different mechanism of action of impurities testing materials. The relationship between the coupling degree of different materials and coils was studied, and the method to improve the detection sensitivity was found out.