Abstract: Sublevel caving method without pillar is a high efficient mining method which is widely used in underground mining of metal mines. Such problems as high ore loss and dilution， poor recovery effect are usually appeared during ore drawing under the overburden. In order to solve these problems， a great deal of researches have focused on the theory of ore drawing， the structural parameters， the formation of overburden and the technology of ore drawing. In sublevel caving without pillar， the size of ore chute has a significant effect on ore-drawing effect and it is an important factor that causes high loss and dilution under sublevel caving without pillar. In order to further study the effect of the height and width of the ore chute on the ore yield and the reverberation of waste rock， physical ore-drawing experiments with 12 different ore chute sizes were carried out by single-pass single-stage physical ore-drawing model.The results show that adequately increasing the width of ore drawing hole or lowering the height will increase the amount of pure ore， improve the recovery rate of ore and reduce the dilution rate. When the width of ore chute is less than 5m， and its height-width ratio is ranging from 0.7 to 1， the waste in-ore rate is lower.

Key words: Pillarless sublevel caving method, Sizes of ore chute, Ore drawing effect, Recovery, Depletion