The advantage of the ICCG method for solving large sparse matrix is taken in the CN-FDTD equation solving. The CN-ICCG-FDTD can accelerate iteration for numerical calculation, and reduce memory overhead. Maxwell's equation of the electromagnetic wave in dispersive medium plasma is deduced from the CN format after being differentiated in the time domain, the FDTD method become unconditionally stable. In this process, a large sparse matrix is generated. As for solving such matrix, ICCG method has sufficient advantages. In ICCG method, convergence is so fast and stable that it is quite easy for computer programming. In addition, data required by ICCG method are memorized in a computer in the format of the one-dimensional compression, which helps the computer memory save a large amount of capacity, especially when the issues are rather complex to cope with, this algorithm will display such strength. With these advantages, ICCG method is able to calculate the reflection coefficient and the transmission coefficient of electromagnetic waves in plasma as well as the phase angle of them. The calculation indicates that the time step required by CN-ICCG-FDTD method has eliminated the constraints of the CFL, thus shortening the required time, making the calculated result stable and accurate, and improving the efficiency of programming. (C) 2014 Elsevier GmbH. All rights reserved.