The auxiliary shaft tunneling of Tashan Coal Mine belongs to the dangerous zone under pressure. In order to eliminate the potential threat of Ordovician limestone water inrush from the floor during the tunneling process, the water outflow from the borehole of the Ordovician limestone aquifer at the floor of the auxiliary shaft's sump floor are analyzed through drilling design and construction, and then the design and construction of grouting reinforcement is carried out. Finally through the water pressure test before and after grouting to analyze the treatment effect to ensure the safety of the auxiliary shaft. The results show that 17 boreholes are symmetrically and evenly arranged within 30m of the shaft for exploration. The data of borehole water yield, water pressure and water temperature are analyzed in detail. It is concluded that the borehole water yield and water absorption increase from northwest to Southeast, and the water yield of five boreholes in the southeast is greater than 4 m3 / h, indicating that the water yield of Ordovician limestone aquifer in the southeast of the shaft is greater than that in the northwest, and the fracture development in the southeast is stronger than that in the northwest, but except for some boreholes, The water absorption of all boreholes is lower than 0.01 L/min?m?m, indicating that the overall fractures in the exploration area are not developed;The design adopts cement single liquid slurry. The water cement ratio of most boreholes is 3:1, and the slurry concentration is about 1.2 kg / cm3. Some boreholes in the southeast can increase the water cement ratio, improve the slurry concentration, and carry out secondary grouting;From the perspective of grouting volume, the grouting volume gradually increases from the boreholes in the northwest to the southeast. Especially in the five boreholes in the southeast, the grouting volume reaches the maximum, which is positively related to the water yield and water absorption of the boreholes;Through the water pressure test to detect the treatment effect, the water yield and water absorption after grouting are far less than those before grouting, and the water absorption after grouting is less than the standard value of 0.01 L/min?m?m, which meet the required grouting completion standard, indicating that the cracks in the coal seam have reached the role of filling, reinforcement and plugging.