Abstract: As a high-precision, high-stability and high-fidelity time-domain numerical algorithm, the symplectic finite-difference time-domain (SFDTD) method has been widely used in many disciplines as a mature numerical calculation method. The paper mainly introduces the construction of SFDTD algorithm, numerical optimization and related key technical processing. Focusing on the optimization methods of the difference approximations both in spatial and temporal direction, local correction methods for discontinuous boundary and curved metallic surface, and three key techniques that are indispensable in time domain electromagnetic simulation, namely total fields/scattering fields (TF/SF) technique, perfect matched layer (PML) and near-far transform technique. At last, the applications of SFDTD method in electromagnetic simulation, quantum mechanical solution and multi-physic problems modeling and analysis are also introduced.