A novel FDTD method, Shift-Operator Finite Difference Time-Domain (SO-FDTD) is promoted. Propagator matrix method (PMM) is successfully utilized to study the propagation characteristics of EM waves in the nonuniform magnetized plasma sheath model of blunt cone. The results of the two methods are compared and both of results indicate that the external magnetic field changes propagation characteristics of EM waves in plasma, broadens the transmission bandwidth and improves the transmissivity of EM waves, which can be perfectly applied in re-entry communications.