Abstract: Under the condition of the symmetry of applied axial, the general solution of Laplace equation is obtained in spherical coordinates. According to the relationship of boundary values, the potential function at each zone of medium spherical shell in uniform external field is solved. A discussion on the characteristics of field dis- tribution with the result of magnetic screening effect of medium spherical shell is also given.

Key words: Laplace equation, relationship of boundary value, electric potential, magnetic marking poten-tial, electric field strength, magnetic intensity, magnetic screening coefficient