本文从磁荷概念出发，利用磁荷与电荷之间的相似性，由静电学知识直接能给出空间磁场和磁势的表达式.再引入

磁壳的概念，利用磁壳的一个简单性质和与电流回路的等效性，得到稳恒电流磁场中几乎所有理论公式.这种以磁荷角度讨论磁学的路线，是深刻理解磁现象的重要途径.

Starting from concept of magnetic charge，using analogy with electricity and knowledge of static electricity，we write out directly the expressions for magnetic field and magnetic potential produced by a magnetic pole. Then，the concept of magnetic shell is introduced and its important character is discussed. With the aid of the equivalence of a circuit and a magnetic shell，we can seamlessly convert the knowledge obtained from magnetic charge to almost all the theoretical formula for current，which are taught in every textbooks of steady current magnetism. This approach of teaching may help students to understand magnetic phenomena in a simple but insightful way.