This paper discussed the inner coupling and coefficient of mutual induction of electromagnetic system. Based on signal-to-noise theory some technology measures to improve the accuracy of underground pipeline probing in electromagnetic method are suggested here. 本文通过对电磁系统内部耦合关系及互感系数的论述,基于信噪比理论,提出了提高电磁法地下管线探测精度的技术对策;