Abstract: The density identification system of coal and refuse based on image processing is researched and developed in order to distinguish them accurately. Based on the MATLAB,obtained images of coal and refuse need to take homomorphic filtering,median filtering,segmentation and morphological filtering by their feature,so that outline of coal and refuse is got. And then volume of coal and refuse can be calculated by integral method; density of coal and refuse also can be calculated by measured mass,finally,the different density identification of coal and refuse can be made. The experiment results show that this method can quickly,effectively detect coal and refuse in real time.