Abstract: In order to understand the effect of combined polymer depressant on the floatability of aegirite and specularite, the inhibition effects of PEG 400, starch and their mixtures in different proportions on aegirite and specularite in sodium oleate system were investigated by single mineral flotation experiments and zeta potential measurements. The results showed that the depression effect of starch on specularite was stronger while the selectivity was weaker than that on aegirite. The recoveries of aegirite and specularite could be up to 74.80% and 14.18%, when the concentration ratio of starch and PEG 400 was 2:1. The zeta potential change of specularite was significant than that of aegirite when starch was added, and PEG 400 showed little effect on the zeta potentials of these two minerals.