An efficient accuracy-improvement scheme is proposed to analyze electromagnetic problems with conductive medium. This scheme is based on interpreting the alternating-direction implicit finite-difference time-domain (ADI-FDTD) method as a special iterative solver for the Crank-Nicholson scheme. By applying an additional number of iterations to locations with relatively large field variation, the overall accuracy can be improved with little computational overhead. Special treatment of lossy medium in the ADI-FDTD method is also addressed. Finally, numerical examples demonstrate the effectiveness of the proposed method.