Abstract: To solve the problems of high labor intensity, long clearing period and hidden danger of flooding, a safety treatment system for underground water in coal mine is proposed, which is used before the mine water enters the sump to ensure that the clear water enters the sump. The system designs magnetic coagulation reaction system, precise magnetic separation host, magnetic seed recovery device, central control monitoring screen, etc. It realizes sequential sewage treatment and safety monitoring and alarm. The test results show that: the annual discharge of SS can be reduced by more than 2 100 t based on the daily calculation of 1,400 m³ of mine drainage treatment. The total annual saving is 4.78 million yuan.