Abstract: The water environmental isotopes can be used to study the source of groundwater and the relationship between surface and ground water, so that to indirectly judge the interaction of each other. By ¹⁸O, ²H and ³H isotope analysis in Jilin section of Songhuajiang River, with chemical and hydrogeological conditions, it is concluded that the groundwater is mainly from atmospheric water, and is influenced by Songhuajiang River only around 500 m long in urban area. The supply ratio of river water to groundwater in this section is found out. It provides a basis for the control and prevention of water pollution incident.