Abstract: Abstract：Coal slime flotation is one of the effective methods for fine coal slime separation. In order to explore the effect of different density of fine coal on the flotation process, this paper mixed different density of fine coal slime with different proportions into coarse coal for test. The flotation feed and gravity concentrate are used as test coal samples, and the gravity concentrate is used to prepare coarse slime and low density fine slime. The flotation feed sample is prepared into fine coal with different density by flotation and sedimentation test using organic heavy liquid. Under different mixing ratios, the best dosage test was carried out first, and then the flotation speed test was carried out for different flotation feed with the best dosage. Through the test, it is found that the effect of low density fine coal on flotation is not obvious; When medium-density fine-grained coal exists, the effect on the flotation speed of coarse coal is not as obvious as that of low-density fine-grained coal; High-density fine-grained coal will greatly reduce the quality of flotation clean coal through entrainment.