From the view of systemic theory, based on the water cycle character, the paper puts forward the quantitative concept of water sustainable utilization in Tarim basin, and builds up the System Dynamic (SD) model of water cycle in Tarim basin. From the model the conclusion can be drawn that water resource is decided by the quantity of precipitation and solid water from the mountains and the precipitation is decided by the recycle coefficient and water storage of the system. The computer simulating results show that the water storage decreased and water system degraded with the temperature rising, and the water system is sensitive to the recycle coefficient and that value is very small compares to the mean value of the whole country. Consider the unique topography and characters of climate system of the basin, the ways to impact the water cycle artificially in Tarim basin are proposed.