Abstract: The process of ore-drawing in block caving is completed under overburden. In the process of ore-drawing, the waste will move out in the form of mixing into the drawing ore. In this case, drawing dilution appears. It makes clear that there are two reasons for drawing dilution based on the research, one is the dilution on the surface between ore and waste when the drawing reaches the interface, the other is the advanced dilution which is produced by osmosis of the small grain of waste. Research of the text is based on experiments, which use different compositions of ore and waste separately. Through the experiments of ore-drawing, the effect of the heterogeneous degree of caved ore and rock on the drawing dilution is investigated, it can give guidance to control the ore-drawing.