Abstract: In order to research the lagging water inrush caused by the hidden fault affected by coal mining on the floor,based on the theory of mine pressure and rock formation control,in view of the different spatial position relations between the hidden fault on the floor and the stope working face,the influence of mine ground pressure caused by mining on the water pressure was analyzed,the law of the increase of hydraulic pressure in the fault and the calculation formula of fault water pressure were obtained,the influencing factors of fault water pressure change were analyzed.The results show that the water pressure in the fault decreases with the increase of fault dip,the water pressure in the fault affected by mining increases linearly with the increase of the minimum principal stress and support pressure.Based on the different spatial position relations between the hidden fault and the stope working face,analyzed the mechanical reason of water inrush caused by the hidden fault on the floor affected by coal mining,the researching results can provide the theoretical basis for the prevention and treatment technology of water inrush caused by the hidden fault on the floor.