Abstract: A high sulfur lead-zinc ore from Inner Mongolia of China contains Pb of 3.62%, Zn of 5.09%, Ag of 79.3g/t and S of 18.49%. This type of ore used selective flotation in the on-site production, recovering Pb of 85.82%, Zn of 89.53% and Ag of 56.38%, respectively. To improve the recovery rates of Pb and Ag, a bulk flotation process was studied according to the processing mineralogy of the lead-zinc ore. The results indicated that the lead-zinc ore had a complicated associated relationship, and the particle size of galena was finer than that of sphalerite and pyrite, which made it difficult to liberate the valuable mineral fully. A new process that Pb and S mixed flotation followed by Pb flotation separation before regrinding and Zn selective flotation from the tailings of bulk flotation was adopted to recover the lead-zinc minerals in the ore. Under the optimal condition determined by the experiments, the grade and recovery of concentrates obtained from the closed-circuit tests on the laboratory scale were 54.41% and 88.03% for Pb concentrates, 48.27% and 90.45% for Zn concentrates. The content and recovery of Ag in Pb concentrates was 1 213.8 g/t and 61.98%, respectively.