Abstract: From view point of airsea interaction, in South Asia, winter and summer monsoon affect ocean current and sea temperature of neighborhood sea area, and ocean (especially ocean inclined temperature layer) also affects monsoon by redist ributing heat flux and sea temperature. So it is significant to research South Asianai-rsea interaction by dynamics method for underst anding deeply the strongness or weakness of winter and summer monsoon as well as the mechanism of their transition. Nonlinear sea temperature equations and equator balance model were used in this paper. Airsea interaction was introduced to the sea temperature equations, thus an ocean-atmospheric coupled model was made. The model contained two physical process:different imposed heat of land and ocean to at mosphere is the basic drive of monsoon; the distributing of sea temperature was changed by the wind blow flow of South Asian monsoon. This model is simplified to be the truncated spectrum model by low-order spectral method, which was easy to be discussed. Multi equilibrium states and stability theory were used to discuss that winter and summer monsoon in South Asia affect sea temperature seasonal change of neighboring sea area respectively, and to discuss airsea interaction and sea temperature long it udinal grads had an effect on monsoon.