The floor water inrush coefficient of No.2222 mining face is close to the critical value and a high possibility of floor water inrush occurs due to insidious faults in Xingdong coal mine. This paper aims at solving the above problem, and ESG micro-seismic monitoring system was applied to monitor the forming process of water inrush pathway. Besides, the space location of water inrush pathway was obtained by a developed micro-seismic analysis system CMMA-3D. Hence, this provides significant guidance for targeted grouting and safe mining above the confined aquifer. The mechanism of water inrush through insidious faults was analyzed based on fracture mechanics and then a formula was deduced to calculate insidious fault propagation length. The propagation laws of different types of faults, including normal fault and reverse fault, were achieved. When the insidious fault is a normal fault, its propagation length ?l is positively correlated with confined water pressure p and lateral pressure coefficient . When the insidious fault is a reverse fault, its propagation length ?l presents the variation tendency of decrease-increase with the increase of confined water pressure p. The permeability of floor fractured zone decreases with the increase of compaction degree of caving rocks, which reveals the reason for water irruption reduction of a later stage in No.2222 mining face.