Abstract: Under the influence of mining, surface water and soil were seriously polluted by the acid mine drainage of Lujiang alunite mine. However, due to the long history of mining development, the mining and collapse of the mining area are serious, and sources of the acidic drainage is not clear, which seriously affects the process of pollution control in mining area. Water samples from different water bodies of alunite mine were collected, such as fissure water, well water, channel water, subsidence area water, rain water, adit water and so on, analysis of characteristics of hydrogen and oxygen stable isotopes was carried out, the direct comparison method and MixSIAR model were adopted to explicit sources of the adit water and the contribution ratio of different water to it, on this basis, combined with testing results of different water quality,alum ore and slag composition, the formation mechanism of acidic drainage in adit was explored. The results show that water in subsidence areas mainly comes from rainfall, but it is greatly affected by evaporation, and it is relatively rich in heavy isotopes, which is quite different from the stable isotopic composition of hydrogen and oxygen of groundwater. The precipitation can recharge the shallow groundwater, but it has a certain hysteresis effect. The precipitation and fissure water may feed the channel water and the channel water may also feed the shallow groundwater. Well water, fissure water, channel water and rainwater may be the main replenishment sources of mine adit water. For the contribution ratio of different water bodies to the adit water, the results of the first sampling in descending order are rainwater 39.1%, groundwater 36.4% and channel water 24.5%.The results of the second sampling in descending order are underground water 56.6%, channel water 30.9%, and rainwater 12.5%. The contribution ratios of rainwater in the two sampling to the mine adit water are quite different, which may be due to the different precipitation. Alum hydrolysis is the main formation mechanism of acidic mine waste water, and pyrite oxidation is also one of the reasons for forming acidic mine waste water. The goaf above the adit provides good conditions for the formation of acidic drainage —plenty of oxygen and water. Those results should provide scientific reference for acid mine drainage pollution control, soil related risks reduction and ecological restoration.