Abstract: The Finite Difference Time Domain (FDTD) method is essential in computational electromagnetics due to its simplicity, efficiency, and ability to handle complex media. This article introduces the proposal, development, and improvement process of FDTD algorithm; Detailed introduction of the research progress of FDTD method in complex environment radio wave propagation, electromagnetic coupling calculation, nuclear explosion and lightning pulse propagation, and underground target detection in China; Finally, the exploration and application of FDTD algorithm by Xidian University are introduced.