There are hidden safety trouble due to fired area and mined-out area in the stringer lode zone of Tongkeng Mine,so it is very difficult to recovery the ore pillars in this area.In this paper,the mining technical characteristics are analyzed.The complex technical problems of mining the pillar group which is left in the hidden danger area are solved by applying high efficiency block-forced caving method with cluster large drilling holes blasting and such safety measures as flexible shockwave resistance waml,even ore drawing and covering in collapsed area,finally the purpose to eliminate hidden safety troubles in the fired area has been achieved.