Abstract: A zero-dimension energy budget model, in which the annual mean global sea-surface temperature and atmospheric temperature in the boundary layer are chosen as climatic variables, is proposed.The effects of some physical parameters (the effective emissivity of the atmosphere, the albedo of the surface, the transmissivity of the atmosphere, etc.) on the climatic system states can be examined.The results show that the equilibrium states and stabilities are related to the feedback of the albedo of the earth and atmospheric effective radiation quotiety.On the modern climatic condition, the effect of the appropriate nonlinear negative feed back together with CO₂, vapor, cloudiness, can help the climatic state tend to be stable.The deviation equations of the equilibrium in the modern climatic sy stem corresponding to this model are used to investigate the distribution of the climatic sy stem under the influence of parameters α₂^w and I₀.