Based on the full understanding of utilization situation of water resources in Jiangsu Province, a numerical model for water use structure is established by using the system dynamics and analyzing the interaction between various subsystems. Regarding the water use structure as the output of the model, sensitivity analysis of the model parameters is conducted to obtain the important decisive variables for water use structure. According the high, middle and low growth rates of GDP and the development speed of the current economy, four development schemes are designed and simulated. The relationship among growth rate of regional economy, total water use and water use structure is analyzed so as to provide reference for the rational planning of economic development and the optimization of water resource allocation in Jiangsu Province.