This paper introduces the mineralogy of a fine-grained Cu-Mo sulphide ore, and the relationship between grinding fineness and flotation performance. Results show that the grinding fineness is a key factor affecting the recovery of copper and molybdenum. The result of one stage grinding and flotation is much better than that of grinding and flotation by stages, because an over grinding of chalcopyrite caused by regrinding of Cu-Mo bulk concentrate can be avoided. Finally, a simple flowsheet has been developed, that is, one-stage fine grinding of raw ore to 90% -0.074mm, and a bulk flotation to produce a bulk concentrate by one-stage roughing, two stages of cleaning and one-stage scavenging, followed by three times of Cu-Mo flotation separation. When the feed contains 0.50% Cu and 0.19% Mo, the obtained copper and molybdenum concentrates assay 19.23% Cu and 48.53% Mo with the recoveries of 85.5% and 90.96%, respectively.