Abstract: The finite difference time domain (FDTD) iterative formula under the condition of one-dimensional transient magnetized plasma are deduced. Based on the metal cavity model, the frequency drift characteristics for electromagnetic wave in transient plasma are analyzed. The analytical solution is also given according to the electromagnetic wave theory. By comparing the FDTD numerical solution with analytical solution, the accuracy of the FDTD method is venified, and the frequency drifts rules for electromagnetic wave in transient plasma are obtained.