Abstract: Dual time stepping technique was introduced into the finite volume time domain (FVTD) method which is a high precision direct numerical solvers for time dependent electromagnetic fields controlled by Maxwell equations. As an unsteady time marching technique, the time precision is determined by physical time step, stability criterion is guaranteed by steady sub-iteration time step in this method, as a result, the physical time step was relaxed which ordinary limited by explicit time scheme and grids, the computational work is also decreased. The computation of canonical electromagnetic scattering problem demonstrated that the computational precision is conserved and efficiency is also increased; by the rational choose of physical time step, the maximum step and convergence criterion of sub-iteration in this technique.