This paper investigates the interaction between groundwater and groundwater-dominated Crescent Spring in an aeolian sand environment to determine the drainage source of groundwater for the lake using hydraulic gradient and isotope analysis methods. The precipitation is found to have an insignificant effect on the lake in an arid climate environment. Hydrogen and oxygen isotopic evidence presents at least two aquifer contributions that recharge 87% and 13% water supply of the lake, respectively. The flow direction of groundwater is theoretically established based on the hydraulic gradient and isotope analysis methods.