Abstract: In arid and semi-arid areas, sedimentary basins are the main carriers for water-supply of production and living of human being. In order to find out the change characteristics of groundwater flow systems in a basin under the condition of the change in the water flow density, it is necessary to simulate the groundwater flow systems in the basin under the condition of variable density of water. In this paper, a sand box physical model is used to simulate the change chatracteristics of groundwater flow systems under the condition of changing regional water density. The results show that with the increasing regional flow density, the flow velocity and circulation of the regional flow system decreases, and the streamline distance and the runoff depth also decrease, while the flow velocity and circulation of the local flow system increase. The results also show that the increasing regional water density will inhibit the development of the regional groundwater system and enhance the local flow system. This study places its emphases on the influence of the change in regional water flow density on the groundwater flow system in the basin, and obtains the variation law of the groundwater flow system in the basin under the condition of changing regional water flow density through the physical experiment simulation.