Abstract: With the increase of mining depth，the engineering geological and hydrogeological condi⁃ tions of mining activities are more and more complex，and the difficulty of floor water disaster prevention and control is increasing.The water inrush mechanism of complete coal seam floor on confined aquifer under min⁃ ing disturbance is still unclear. In order to further study the mining failure of complete coal seam floor and the formation process of water inrush mechanism and reveal the mechanism of Ordovician water inrush from floor，taking 21605 mining face of Binhu Coal Mine as the research object，the formation of water inrush mechanism and the law of Ordovician confined water lifting under mining disturbance are simulated and ana⁃ lyzed.The results show that in the early stage of working face mining，small cracks appear in the floor strata under the action of mine pressure. With the expansion of mining scope，the cracks continue to develop and connect with the lower fourteen ash aquifers. Under the action of confined water pressure，the Ordovician limestone water is gradually guided along the hidden fissure to the fourteen limestone aquifer，which commu⁃ nicates the floor failure zone of the working face and then the floor water inrush occurs.The evolution process of Ordovician limestone water inrush from complete coal seam floor is divided into four stages of progressive recharge，fracture expansion，seepage increase and channel formation.The theory of "five zones" of complete coal seam floor above confined aquifer is put forward，which are floor mining failure water conduction zone， mining fracture hyperplasia zone，complete rock zone，confined seepage rise zone and confined original rise zone.

Key words: underground mining, water inrush of floor, water inrush mechanism, numerical simulation