In traditional equivalence principle algorithm (EPA), the unknown currents of the scatterers are replaced by equivalent electric and magnetic currents on the virtual equivalence surface. In this paper, a single electric/magnetic current on the equivalence surface is used to generate the scattered field. According to the extinction theorem, a relation between the equivalence electric current and magnetic current can be established, which is similar to generalized impedance boundary condition (GIBC). Therefore, only the electric/magnetic current is the unknown in the final EPA formulation. Numerical results for the array structures are obtained to demonstrate the accuracy and efficiency of the proposed method.