Karst groundwater is not only an important source of water for living and production, but also an important geological force, which has a significant impact on the history of karst evolution. Study on hydrochemical features and evolution laws will provide a scientific basis for karst water resources and karst ecology protection. Taking the karst groundwater in the gorge area of the slope zone of the Sichuan- Yunnan Plateau as the research object, combined with the hydrogeological conditions of the study area, the chemical characteristics of groundwater in the karst water system of the Longzhuaba River and the karst water system of the Luoze River were compared and analyzed. Through the conventional groundwater chemical composition, hydrogen and oxygen isotope analysis and hydrogeochemical reverse simulation, this study indentifed the groundwater chemical types and defined the main ion source and recharge characteristics of karst water and the water- rock interaction process. The research shows that the karst groundwater originates mainly from atmospheric precipitation, ion source from rock weathering, and materials from limestone and dolomite limestone. The water- rock interaction is controlled by mineral calcite, dolomite and gypsum precipitation and dissolution. The mineral saturation index in the karst water system of the Longzhuaba River is close to saturation, and the karst development tends to stagnate. While the mineral saturation index in the karst water system of the Luoze River is in the state of unsaturated to saturated fluctuation, and the karst is still developing.