Abstract: The habitat and that below formulate the most important environmntal criteria for agricultural production and are strongly affected by the environmental conditions in larger scale. According to the stratification of ecological relations in theory and practice of ecology in Yuanshuan County of Hunan Province, it is necessary to control the ecological environment in more extensive range for obtaining a stable and high yield. The author analysed the frequency, distributom and developmental tendency of main natural calamities with data over the last 27 years. The results showed that the economic loss from natural disasters could be expressed in an exponential curve which indicated the obvlons degradation of the quality of agro-ecological environment. A system of preventing and reducing natural disasters has been suggested based on the protective forest systems. A holistic system with forests of windbreak, farmland shelter-break, watershed, soil conservation and timber forests etc.was proposed The direct economic benefits of that system was forcasted in the last part cf this paper.