Abstract: To solve the problem of the scarcity of coking coal resources in China,improve the comprehensive utilization rate of coking coal resources,taken the coking middlings（size fraction is 50 ~0 mm,ash content is 34.56%） from a heavy medium separation process in Xinliu coal preparation plant,carried out the microscopic maceral analysis,X-ray diffraction analysis,conventional crushing,deeply grinding and selective flocculation flotation tests.The results showed that there are more clay minerals in middling coal,and the disseminated size is so fine that caused gravity separation and conventional flotation process is unable to effectively separation.After deeply grinding,utilizing heavy-liquid refuse discharge plus selective flocculation flotation separation process,could get clean coal which ash content is 11.96%,yield is 48.43%,flotation perfection index is 41.53 and combustible recovery reached 60.87%.