Abstract: In order to avoid mine flooding accidents caused by the accumulation of water and ensure coal mine safety production, for the water accumulation problem of 2^# and 6^# coal seam unknown goaf in the upper part of 10^# coal seam in Shengli Mine, a judgment method for the threat level of upper goaf water acting on lower coal seam mining is proposed. The risk is divided into four classes: original rock permeation type, similar original rock permeation type, inrush type and outburst type and the definition and judging criterion of each type is proposed. According to the criterion, theoretical calculation and numerical simulation are adopted respectively to analyze the risk of 2^# and 6^# coal seam goaf water acting on 10^# coal seam mining. The analyzed results show that the risk of 2^# coal seam goaf water acting on 10^# coal seam belongs to similar original rock permeation type and the risk of 6^# coal seam goaf water acting on 10^# coal seam belongs to water inrush type.