Abstract: Chenjiazhuang Spring is located on the Yongding River. Since the ecological environment improvement project of Yongding River was carried out, the spring flowed out in 2019. In order to protect and manage Chenjiazhuang Spring, realize the ecological environment management of Yongding River and regional water resources strategic reserve, spring origin analysis and spring domain division were carried out.The recharge source, recharge elevation and recharge temperature of the spring were obtained by testing and analyzing the isotope and hydrochemistry samples of rainwater, river water and groundwater in the spring area;On the basis of the above analysis, combined with the regional geological and hydrogeological conditions, delimit the spring catchment area.The results show that the Chenjiazhuang spring exists in the Ordovician limestone aquifer,the regional karst groundwater recharge source is atmospheric precipitation and Yongding River water, the spring is an exposed erosion overflow spring, the spring recharge elevation is 736 m, the recharge temperature is 13.12℃,the catchment area of the spring is 30.6 km².