The properties of tailings of magnetic separation from somewhere in Yunnan were analyzed.By flotation experimentation,the effect of different kinds and dosage of organic depressants on the arsenic reduce of the sulfur concentrate was investigated.The cleaned arsenic-sulfur concentrate was processed with the closed-circuit flowsheet of one stage roughing,two stages cleaning and one stage scavenging,and a sulfur concentrate containing sulfur of 43.85% and arsenic of 0.58%,and with sulfur recovery of 54.95% was obtained.The cumulative sulfur content and arsenic content of the magnetic concentrate and the sulfur concentrate is 39.33 and 0.45% respectively,the cumulative sulfur recovery is 80.39%.The results indicated that MF can effectively reducing arsenic in the sulfur concentrate,the study constructed a solid foundation for further exploitation and utilization of this ore.