Abstract: The water-inrush from coal floor is led by the actions between mining stress and confined water pressure Because developing and mining upset the balance of crustal stress,some regions of concentrating crustal stress will release the energy of strain to reach new balance,so that the rock mass structure is changed The actions of confined water pressure and coal floor retainer is mainly bath rock mass volume expanding and the rock softening This paper introduces comprehensive technique of measuring rock mass stress,which is composed by the in-situ measuring technique of the rock mass stress,measuring technique in trinity axis permeater instrument in laboratory and simulating technique of the finite element;and the applications in the prediction of water-inrush from coal floor.