Tailings of sulfur ore grade is 2.13%, and the amount is about 5 400 t/d in Yinshan plant. The sulfur concentrate is recovered from the full recovery of sulfur mineral resources in the tailings. The technical index on the sulfur concentrate grade is 45.52%, and the recovery rate of 47.88% is obtained. Condition tests are done on activator, flotation density, depressant and collector of sulfide minerals, in order to improve the sulfur concentrate grade and increase the cleaning times. Finally, this paper confirms the return process, i.e. two refinement, one roughing, one scavenging, and the middlings order, with concentrate grade of 45%, butyl xanthate 35 g/t and foaming agent 20 g/t by not adding any depressant and activator to handle the tailings. Based on the closed circuit test results, this paper recommends the use of cyclone pre classification of industrial process for the recovery of flotation increase density.