Abstract: Based on Lorenz's moist general circulation model, the topography effect is introduced in the model, and it is properly simplified. A nonlinear and dissipative system decribing atmospheric motion has been obtained in approximation of low order. The multiple equilibria of moist baroclinic atmosphere in the parameter space, the flow patterns and longitudinal oscillation of south Asia high by thermal forcing and. nonlinear interaction of general circulation are studied in this paper. The results show that 1) the west pattern, east pattern and beltlike high are the primary equilibria flow patterns of south Asia high, 2) the transformation of flow patterns between east and west flow pattern is a discontinuous displacement, and is a process of resetting new flow pattern by rapid exchange flow field.