According to the characteristics of Ordovician lime water hazard in North China Coalfield, through the analysis of regional hydrogeological conditions, comprehensive exploration methods such as geophysical exploration, drilling, geochemical exploration and drainage test were used to find out the water-rich and water-conducting structure of the floor aquifer in the working face area. With FLAC3D software numerical simulation, combined with the rock pressure analysis results of water inrush mechanism of Ordovician lime from floor, the influence of Ordovician lime water disaster on mining face was studied and evaluated comprehensively. Monitoring and early warning measures were adopted in the process of mining to realize safe mining of working face in complex hydrogeological conditions.