Abstract: For a rock-burstoccurred in horizontal slice mining face in steeply-inclined and extremely-thick coalseam of Wudong Colliery，micro-seismic monitoring result showed that rock pillar between B₂coalseam and B₃coalseam was the main rockburst danger source.Applying rock strata structure breakage and strength weakening thinking，surface blasting and underground water injection of rock pillar was practiced.Monitoring results showed that surface blasting and underground water injection effectively reduced energy and stress concentration degree of rock pillar，and that rock-burst was prevented effectively.