Abstract: To solve 3D parabolic equation efficiently (PE) and accurately, an iterative method for solving 3D PE is proposed. In this method, finite difference (FD) approximation is applied. The proposed method retains the character of the alternating-direction-implicit (ADI) method. The numerical error caused by the split term of the proposed method is considered in the process of derivation. The proposed method can improve the calculation accuracy compared to the ADI-PE method and Crank-Nicolson parabolic equation (CN-PE) method. A certain accuracy can be achieved by several times of iteration. This method is efficient and accurate for solving 3D PE.