Abstract: By using a quasi-geostrophic, two-level baroclinic highly truncated spectral model on a β plane, computations have been made in the cases with diabatic heating differently in basic current. The results are as follow: ① When the values of the parameter relevant to the external thermal forcing are selected properly, the establishment and oscillation of South Asia High may occur. On the other hand, the “chaos” phenomenon may appear if the greater values of the parameter of thermal forcing are taken. ② When the land-sea thermal contrast is reduced to a certain extent, the South Asia High tends to be in equilibrium state. ③ South Asia High cannot occur if there is only medional inhomogeneous external thermal forcing