Abstract: This paper aims to explore whether the old goaf water of No. 5 coal seam threats on No. 15 coal seam in initial mining lower coal group water inrush in Zuoquan Wulihou Coal Industry Co., Ltd. It uses the lower coal group of initial mining coal working face as the background, and comprehensively analyzes the geological and hydrogeological conditions in the study area. It examines the spatial distribution characteristics of two coal seams for roof and floor. The deformation and destruction model is set up after mining. Three possible conditions are put forward for the old goaf water whether threat. On this basis, the quantitative parameters of the height of the water-conducting fracture zone at the first mining face of the No. 15 coal seam in the lower coal group and the failure depth of the floor of the No. 5 coal seam in the upper coal group are obtained using the empirical formula and numerical simulation method, and comparison with the spacing between the two coal seams revealed by the boreholes. It is considered that after the mining of No. 15 coal seam of the lower coal group, the water in the goaf of No. 5 coal seam of the upper coal group is likely to pass through the water conducting fractured zone under normal conditions. It is suggested that drainage should be carried out before mining. The research results have a good reference value for the prevention and control of water damage in the roof old goaf of the first working face in the lower coal group.