Abstract: The non-pillar sublevel caving method with large structural parameters used in Mao Gong Iron Mine is of high rate of dilution and loss, and the ore recovery rate is less than 50%.Aiming at this problem, this paper analyzes the influence of the caving step on the mining index by means of the matching relationship between the shape of caved ore body and the drawn-out ore body, then through the physical simulation experiment in laboratory, the mining index such as the volume of pure ore drawing, ore recovery ratio and rock mixing ratio are studied under different caving step.The results show that the mining index under caving step of two row of blasthole is better than that under caving step of one row of blasthole.The research has guided significance for production of the mine.