Abstract: Mining sequence in pillarless sublevel caving has a great influence on ore loss and dilution.Underground mining in Dahongshan iron ore is affected by open pit mining.With 70° as the ore boundaries，recoverable ore must be recovered first，then the left ore is recovered until the pressure over the left ore is moved.Current researches on loss and dilution are mostly based on the case of mining upper sublevel first and then the lower sublevel.But research on loss and dilution resulting from high fall formed by first mining one side then mining the other side is less.The loss and dilution rate by above stages of ore removal and normal mining sequence was compared using laboratory physical simulation.The results showed that the loss and dilution by stages of ore removal was lower by 7.1 percent point than that of the normal mining.Analysis found that the rock contact zone by normal mining was continuous，while the contact zone by staging was cut off into two different elevations of "V" shaped，which lead to the waste rock surface increased，resulting in high dilution rate than the normal.The study also found that as the ore drawing gap increased，the recovery-dilution index decreased slowly.It is finally recommended that the mine should reduce the fall as much as possible or use the low dilution ore drawing to retain the 70°ore-rock contact zone in order to control the loss and dilution.

Key words: Pillarless sublevel caving, Mining sequence, The ore loss and dilution, Similar simulation, Mine rock contact zone