Abstract: By identifying the risk factors of in-situ immersion groundwater pollution, a risk assessment model for in-situ immersion groundwater pollution based on the unascertained measure theory was established. The information entropy theory was used to determine the weight of the evaluation index, and the confidence identification criteria were used to evaluate the groundwater pollution Risk level. which included 14 major factors, such as the pH value, dissolved solid (COD), sulfate, chloride, Permanganate index, nitrate, ammonia nitrogen, fluoride, six valence chromium, the monitoring and collecting system for the mother liquid of the tunnel receiving liquid, horizontal hole monitoring and receiving system and vertical hole monitoring and collecting liquid, daily rainfall of meteorological system and monthly cumulative rainfall. Then, the unascertained measure function of the index was obtained, the weight of the evaluation index was determined by the information entropy theory, and according to the credible recognition criteria, the risk assessment of groundwater pollution was carried out before mining, leaching, mining and private mining areas. The evaluation results are in good agreement with the actual situation of the mine. The study shows that the selection of model indexes was reasonable and the unascertained measure model was reasonable. The model has certain practical application value.