Hydrogen and oxygen isotopes are widely used as tracers in hydrology, hydrogeology, ecology, soil science, biogeochemistry and other research fields. Coal mining has a certain disturbance to the surface ecology. In the process of ecological restoration and treatment in coal mining area, the problem of ecological water level is an unavoidable scientific problem. In this study, Shendong mining area is selected as the research area. In order to explore this scientific problem, a certain abundance of hydrogen and oxygen isotopic water is artificially put in as a tracer to carry out in-situ tracer research. According to the hydrogen and oxygen isotopic values of plant water extracted and tested from the stems and leaves of surface plants, the limit depth of plant water absorption and reasonable ecological water level are analyzed. The results show that, firstly, the soil moisture content changes little from the surface to 2.5m, and gradually increases and peak at about 2.5m-3.5m, and then decreases and tends to be stable to the deep; Secondly, by analyzing the isotopic characteristics of plant stems and leaves, the limit depth of water absorption of Artemisia annua is 2.5-3M; In addition, the mixsiar model was used to analyze the water content of which soil section was mainly used by Artemisia annua. The soil section at the depth of 240cm was divided into 12 layers, of which the water contribution rate of 60-80cm, 80-100cm and 100-120cm was relatively low, and the contribution rate of other layers was nearly 9%. This study provides a scientific basis for ecological restoration and treatment in Shendong mining area.