Abstract: The dynamic simulation model while is based on the system dynamic method has been established for the water - saving agricultural system in Guantang experimental area. By designing feedback controlling loop, the 63 parameters are defined in the "SD" model. A tracking of the computer simulation shows the dynamic action and the main changing trend of the system variables. The result of simulation indicates that the effective irrigation area can reach 76 percent while the groundwater level from the ground level is controlled within 5.5m.