Abstract: Using the RFPA soft, to the T112-T115 test mine of 92^# orebody in Tongkeng Mine, the time-varying effecting are simulated and analysised to induction caving roof. The results are showed following:①The steady empty area is up to 4500 m². ②when the fourth order, rock of roof have been avianized, the caving line height is 48m, then the roof must be caving by manual inducation in order to make sure safe mine, the safe height of indcation caving engineering must up 50m to empty. The results of time-varying effecting show that the enclosing rock mass are avianized by the change of mining stope space, the roof is induced fractureing by artificial disturbance in the part roof, and insteability caving in roof, it is effective method to handle empty.