In order to improve the computational accuracy and cost for multi-medium power frequency electric field (PFEF) solved by low order boundary element method (BEM) and preconditioned generalized minimal residual (GMRES)，a hybrid technique combining the high order BEM and fast multi-pole (FM) method has been introduced to low order BEM. The FM preconditioned GMRES high order BEM is proposed to solve three dimension electric field distribution. The high order BEM model for three dimension electric field distribution is built, and the basic principles and implementation steps of the FM preconditioned GMRES high order BEM are given. The higher accuracy has verified in two medium test models. Part key devices in 500 kV substation is carried out to demonstrate that FM preconditioned GMRES high order BEM is much faster and more efficient than the preconditioned GMRES BEM in the computational cost and the storage of computer. The simulation values of this method are compared with measured values in 500 kV substation. It is found that the max relative error is 8.65%, so this method is suggested for use in large-scale and multi-medium PFEF problems.