Abstract: In order to ascertain the water environment characteristics of the Donggong River Basin in Qinhuangdao, the atmospheric precipitation, groundwater and surface water in this basin were taken as the research objects. Through the analysis of its water chemistry and hydrogen-oxygen stable isotopic characteristics, the characteristics of its temporal and spatial changes and the characteristics of atmospheric precipitation, groundwater and surface water are revealed. The results show that: (1) The water chemistry of groundwater (Quaternary pore water, karst water, fissure water) and surface water (river water, spring water) in the Donggong River Basin are more abundant in dry periods than in wet periods. The water chemistry types in the rich season are HCO₃-Ca type, HCO₃·SO₄-Ca type and HCO₃-Ca·Mg type mainly; the water chemistry types in the dry season are HCO₃-Ca type, HCO₃-Ca·Mg type, HCO₃·SO₄-Ca type, HCO₃·SO₄-Ca·Mg type mainly. (2) The change of ion content in Quaternary pore water and spring water in the study area is greatly affected by the season, and the change in ion content in dry season is more significant than in wet season; the ions in karst water and fissure water have a small change range and tend to be stable. The karst aquifer and bedrock fissure aquifer are rich in gypsum, which is the main source of SO₄^2-; Na⁺ and Cl^- mainly come from the easily soluble salts NaCl, Ca²⁺ and Mg²⁺ mainly come from the weathering dissolution of calcite. (3) There is a close hydraulic relationship between groundwater, surface water and atmospheric precipitation in the Donggong River Basin, analysis of the composition of hydrogen and oxygen isotopes shows that atmospheric precipitation is the main source of groundwater and river water, and the spring water mainly comes from karst water replenishment and is affected by evaporation; pores water receives dual recharges from atmospheric precipitation and river water; fissure water is mainly recharged from mountain runoff. The studies have shown that the ion content in different water bodies of the Donggong River Basin is affected by rainfall, temperature and geological background. Different water bodies are closely connected and complement each other for excretion.