Abstract: Beiminghe iron mine is a contact metasomatic skarn type magnetite deposit，and the sublevel caving mining method was adopted. The sublevel height is 15 m and the drift interval is 18 m. These parameters have been used mining the upper orebody，and better technical economical effect was obtained. With the mining depth increasing in recent years，the ore loss rate increase gradually，so the mine needed a new structure parameter. 20 m sublevel height based on trend of subleve development was recommended in this paper，the principle of mining using at least three subleve and the factor of beneficial to recovery residual ore on footwall. Based on calculation using a new measured granular media flow parameter，20 m sublevel is better than the 18 m drift interval. In addition，the transition way of different sublevel is put forward.

Key words: Sublevel caving mining method, Structure parameter, Granular media flow parameter