The author applies covertly and macroscopically the SPAC theory model to the water saving system of well irrigation rice in Sanjiang Plain. Several sub-systems have been taken as a whole large system, such as groundwater, machine well, sunning water pool, channel, field, environment and so on. Through applying modern building models and optimization technique, the author analyzes the mechanism and theory of each subsystem, some mathematical models about groundwater, sunning water pool, channel, water production function, water requirement and available rainfall have been built. At last, through designing the typical demonstration area, the author combines several water-saving techniques into a whole system. Thus, the goal of raising water temperature 5～15℃ , saving water 17.1% and increasing yield 700 ～1 000 kg/hm² canbe reached.