Abstract: According to the works of Kuo and Cho(1980) and Oriistaglio and Hohmann(1984), a modified finite-difference approach technique was presented in this paper for solving time-stepping Maxwell’s equations of an arbitrary two dimension was reduced to a series of one dimension by the methodology of transferring direction was reduced to a series of one dimension by the methodology of transferring direction, and the previous technique was retained in which the boundary condition of an upward continuation at the earth air interface was applied to avoid finding the solutions of the air layer in the grid. Thus the computer’ memory was saved, calculating method was simplified and calculation can speed up. Solutions of various models showed that this method has great calculation precision.