Abstract: The problem of the stability of .the forced Rossby wave packets which are nonlinearly interacted resonantly in the middle atmosphere is examined numerically. The results are in agreement with our theorical analysis. When there is only one forced wave packet with middle wavelength, the stationary state may bifurcates to another stable one. Specially, when the Rossby wave packet with middle wavelength is the only one which isn't forced, there may exist multi-stationary states. The stationary states may generate cusp catastrophe in some domain of the intensity of the forcing. The stationary state that the system can really tends to is not only relateto the way in which the intensity of the forcing varies but also depends on the initial state.