Abstract: A certain lead -zinc ore in Qinghai belongs to low -grade refractory lead -zinc -ore because the content of lead and zinc are very low. The lead minerals associate to zinc and sulfur minerals closely. According to the characteristic of the big floatability difference between lead minerals and zinc sulfur minerals, the selective flotation flow-sheet is adopted. Laboratory test adopts diethyl dithiocarbamate as the collector of lead, with lime, sodium sulfite and zinc sulfate as the depressor of zinc sulfur minerals in lead roughing, using copper sulfate as activator of marmatite after adjusting the pH value of the dehydration pulp of lead tailing to 10.5. The results show that under the condition of raw ore with a lead and zinc grade 2.27 % and 1.17 % respectively, the technical indicators of lead concentrate with lead grade 50.87 % and lead recovery 78.33 % and zinc concentrate with zinc grade 45.30 % and zinc recovery 70.47 % can be obtained from the closed-circuit test.