Abstract: In order to analyze the safety of water damage condition in the mining process of the Carboniferous main coal mining layer in Yanzishan well field, based on drilling and geophysical prospecting methods, the paper studies the hydrological geological conditions of water accumulation in Jurassic goaf overlying Carboniferous mining layer and lower Cambrian limestone water underlying Carboniferous mining layer. The experimental observation of hydrology shows that the salinity of groundwater in the main aquifers is high, and the water yield property is poor, also the runoff of water is slow. The results of transient electromagnetic method show that there are several stagnant water areas in overlying Jurassic goaf. The karst water level elevation is higher than the Cambrian coal seam floor elevation, the No.5 and No.8 coal seams are of mining above aquifer. The calculation results of water inrush coefficient show that the water inrush coefficient of No.5 coal seam is less than 0.06 MPa/m, and the water inrush coefficient of No.8 coal seam is greater than 0.06 MPa/m. In coal mining process, it is key to prevent the overlying goaf water and mine water inrush caused by pressurized water in No.8 coal floor.