Abstract: A stuly on statilily of hard rock pila between the steep inclned seams could be key of the dynamic disaster control infullyrnechanized top coal cavingmining in a horizontal section of steep inclined ultrathick seam. Based on coalseam angle of 871inthe Saouth Mining Block of Wucong Mine in Jrunci Mining Area as study background,dynamics theary was appied to estabish a mechanics modelofthe hard rock pillr between the steep inelined ulrathick seams and a dyramic equaon when the rock pillar was turning was obtained.A FLAC3 Dwas appied to study th distribution law of the inernal stress and stain evolution occured in the rok ilr.The results showed that with the pushing forward of the coal mining face.the turning effect of the roc illar would be more obvious Thne turning of the ock pllarwoud cause the stress concentration effect at the two sides of the cal mining fac. During the turning process of h ock illan ocation ofth second breaking occured would be at the 1/3 location of the inclined length. The monitoring resutsof the site acoutic emisson to the coal mining facegateways at th two sides of the rok pllarshowed the rationa lity of the theoretical analysis and the numeical simulaton. Thus a pan was proided with thepilotcoal mining face to conduc a periodial ouplingfracturing to the rock pillar and could effectively reduce the stress concentration effect of the coal pillar to the coal mining face.