Abstract: No.100-9 ore-body of Baizhangzi Gold Mine is the residual ore-body，it is difficult to recover the ore-body under the influence of the multiple mined-out zones，the poor ore and rock stability，the large rock movement，and a large amount of remained discrete ore.Therefore，the induced caving method with collaborative undercut of the multi-sublevel and double trenches on the bottom is proposed.By analyzing the relationship of caving，the critical caving span and height with the mining depth，and combined with the features of the existing conditions and the ore flow characteristics，the inducing engineering parameters and blasting parameters are determined.The cutting layout in central orebodies and mining towards the ends are adopted.In the situation that the former sublevel mining working face is 6~8 steps ahead of the latter one，The piecewise undercutting drifts are constructed at the same time，and the upper ore body are induced gradually and recovered by the double trenches.And then spray-bolt-mesh combining support is selected and the thickness of caving bedding is 3 m，by which the residual ore can be recovered safely，economically and effectively.

Key words: Recovery of residual ore, Mined-out area, Induced caving, Undercut, Ore-drawing roadway, Trench