Abstract: In the finite difference time domain method (FDTD), the one-dimensional plane wave advancing method and analytical method are studied based on the idea of corner points delay. The results show that the one-dimensional plane wave advancing method and analytical method are both effective; the former one can largely offset the inherent numerical dispersion error of FDTD, which leads to little spill wave, but a large spill wave appears in analytical method; and also that the spill wave can be further removed by decreasing the size of meshes.