Abstract: Fast and accurate identification of mine water source is the key condition to prevent and control mine water damage. This study takes Mindong No.1 Mine in grassland mining area of east China as the research area, collects a variety of mine water source samples, and analyzes the hydro-chemical characteristics of different types of water samples by drawing Piper three-line diagram and Gibbs diagram and ionic proportional coefficients diagram, and qualitatively identifies several types of mine water source. In addition, the proportion of mine water source is quantitatively analyzed by the calculation of hydrogen and oxygen isotopes. The hydro-chemical type of mine indirect water sources (atmospheric precipitation, surface water, quaternary diving and aquifer water I) is HCO₃-Ca, and the hydro-chemical type of aquifer water II is HCO₃-Ca mixed with HCO₃-Na. The hydro-chemical types of aquifer III water and mine gushing water are both HCO₃-Na type, and aquifer III water is the main recharge source of mine gushing water. The formation of Ca²⁺, Na⁺ and HCO₃⁻ in groundwater and mine water is controlled by rock weathering, and mainly comes from the dissolution of silicate minerals such as potassium feldspar, albite and calcium feldspar. Combined with the calculation of isotope tritium content, the relative average age of water in the Quaternary, I aquifer, II aquifer and III aquifer is 18.48, 57.88, 69.24, 69.24 years, respectively. The average age of mine water gushing is 69.24 years, and the average values of δD and δ¹⁸O of mine water are closest to aquifer II and aquifer III water. Mine water gushing is mainly a mixture of aquifer II and III water, accounting for 11.1% and 89.9% of the total mine water gushing, respectively. The mixing ratio is about 1∶9.