Abstract: Presently static equilibrium models are the main numerical weather forecasting models.In recent years with the increase of the model resolution,the development of non-static equilibrium models in China and the introduction of MM5 and other models, the applicability of these two kinds of models in mesoscale at mospheric simulation must be clarified.The error of the simulated frequency of gravitational wave was analized under the static equilibrium postulation.It was indicated that the relative erroris in inverse proportion to the square of horizontal reso lution(ΔX).When ΔX≥20 km,the relative erroris less than 4%.When ΔX≤10 km,the relative erroris probably greater than 16%.Different to the concept just as its name implies,the simulated frequency of gravitational wave under the static equilibrium po stulation is exaggerated,and the computed verticalaccel eration is also aggrandized because of the omission of the inertiaterm.The case resear ches by using the quasi-static equilibriummodel described in this paper where the inertiaterm was corrected also agreed with the conclusion mentioned above.