It is challenging to separate fluorite from calcite due to their same calcium activated sites on their surfaces. The copolymer of maleic and acylic acid (PMAA) was used to inhibit the calcite in the flotation of fluorite. Micro-flotation results exhibited that sodium oleate (NaOl) had a good ability to collect fluorite and calcite in the scope of pH 7-10. The PMAA treatment prior to NaOl selectively depressed the floatability of calcite while allowed the flotation of fluorite, and the artificial minerals mixture plotted that fluorite/calcite could be effectively separated in the presence of PMAA/NaOl. Zeta potential results suggested that NaOl collector was absorbed on the PMAA-conditioned calcite surface but did not adsorb on the PMAA-conditioned fluorite surface. XPS results and calculational chemistry revealed the chemical interaction occurred between calcite surface and PMAA which was attributed to the calcium ions of calcite surface interacting with -COOH group of PMAA.