Abstract: Based on the scientific problem of self-purification of underground reservoirs in 〖JP2〗open-pit coal mines and the self-built experimental platform of artificial recharge of mine water, this paper conducted research on water quality and permeability in the process of artificial recharge of mine water, and the simulation artificial recharge experiment of mine water underground reservoir was carried out. Using a single-variable experimental method, changing the pretreatment method of mine water before storage, combining mine water turbidity, TDS, particle size of suspended solids and SEM scanning electron microscopy before and after recharging, the water quality changes during continuous water storage in underground reservoirs were analyzed. According to the law, the water quality requirements of underground reservoirs were determined, and the main mechanism of self-purification of underground reservoirs in open-pit coal mines was summarized. According to achieved results, the law of media permeability changes in the process of artificial recharge of mine water with different turbidity was studied. The location and type of blockage caused by artificial recharge of water were the first to put forward the contradictory relationship 〖JP2〗between the self-purification of underground reservoir and the permeability of medium. The research results show that the use of coagulation method to pre-treat the mine water can effectively increase the particle size of suspended particles in the mine water through adsorption and bridging. In the process of continuous water storage in the underground reservoir, the turbidity and TDS in the water will be further reduced. However, from the perspective of the change of media permeability, the suspended particles in the water are removed and shortened at the same time. The time when the recharge system reaches the blockage is mainly due to the blockage of suspended matter on the surface of the recharge medium, and the permeability change of the recharge medium has a periodic law. The techniques of 0-5 cm surface dredging and 30-hour periodic reversion can be used as effective means to eliminate the impact of reduced media permeability on the recharge system.