Abstract: A lot of silica rocks exposed from ore bodies in the southern district of Xishimen iron mine，resulting in deposits becoming gently inclined and thin.The mining process of the existing non-pillar sublevel caving mining method in Xishimen Iron Mine is improved.With the principle of three phases stoping，and in the form of upper and lower double working lines，both the upper “lean ore” and the lower “rich ore” can be achieved at the same time.It better adapts to the orebody occurrence and reaches the target of high efficient exploitation.

Key words: Gently inclined medium-thickness ore body, Pillarless sublevel caving method, Double working lines mining, Stope structure, Drift supports