Abstract: By using 2nd order operator-splitting scheme,numerical simulations of nonlinear propagation for a Gaussian gravity-wave packet in time-variant background temperature and wind fields are carried out individually. The simulation results show that the time-variant background fields influence little on the spacial structure of the wave packet, and the polarization relations of each wave disturbance components agree well with that of the linear gravity wave theory. Propagating in a time-variant background temperature field, the propagation paths of the gravity-wave packet are obviously different from the paths derived from the linear wave theory, and the variational tendency of the horizontal and vertical group-velocities are little difference is found in the variation of wave opposite to prediction of the linear theory, and a frequency between the simulation result and the dispersion relation of gravity wave.These indicate that the linear wave theory isn＇t feasible to describe quantitatively the nonlinear propagation of the gravity wave packet in time-variant background fields. While in a time-variant background wind field, the background impacts more significantly on the wave frequency than in time-variant background temperature field, and the propagation paths is more close to the paths of the linear theory than that in a steady-state background field.