Aiming at the abnormal activity of West Pacific Subtropical High(WPSH) inducing the serious flood disaster in 1998, and considering the complex seasonal activity of WPSH in summer, based on the actual geopotential height field time series observational data in 1998, a non-linear dynamic model of WPSH was reconstructed by using the idea of dynamic system retrieval and genetic algorithms. Combined with the synchronous actual weather process, the corresponding dynamic characteristics and variation mechanism of WPSH, such as the equilibrium state destabilization and bifurcation of the WPSH system, were analyzed and discussed. The research showed that due to the advantages of global optimization and parallel calculation of GA, a nonlinear dynamic model could be reasonably and quickly reconstructed, and the reconstructed nonlinear dynamic model of WPSH derived from the actual abnormal case data could be used for describing objectively and explaining reasonably the basic characteristics and the abnormal activity process of WPSH. The dynamic discussion showed that the configuration and diversification of WPSH system equilibriums, such as bifurcation, catastrophe had a good matching with the actual medium short period abnormal activity of WPSH, such as northward jumping and southward droping, as well as double-ridge line pattern. The modality of WPSH geopotential height field induced by multi-equilibriums destabilization was more complex than that of by single-equilibriums bifurcation, and their exhibition patterns were more different. With the forcing parameters increaseing, closing with and exceeding critical value, the WPSH system equilibrium state destabilization or bifurcation would occur. Especially, when the equilibrium state jump/drop from low/high to the high/low value, corresponding WPSH system behaved as a leap northward /fall southward, moreover, when the stable equilibriums state from 1 to 2, corresponds with the pattern of “double-ridges” phenomenon of WPSH, contrariwise, “double-ridges” phenomenon would disappear. A meaningful technique route was provided to the mechanism research and dynamic characteristic discussion for the complex weather system of hardly modeling such as WPSH.