Abstract: The Maxwell's equations are written as normal Hamilton equations using functional variation method.We discretize Maxwell's equations using sympletic propagation technique combined with fourth-order finite difference approximations to construct symplectic finite difference time domain(SFDTD) scheme.The stability and numerical dispersion analysis are presented.The applications of the scheme in electromagnetic scattering are also included.Numerical results are given to show the high efficiency and accuracy of the SFDTD scheme.