Abstract: In order to explore the synergistic effect of OP series surfactants on sodium oleate floating phosphorus and desilication, sodium oleate is prepared by adding OP surfactant with different number of ethylene oxide,which is used in pure mineral flotation test and practical mineral flotation test to select the optimal distribution of OP surfactants and mix proportion.The synergistic mechanism of OP surfactant is explored through the foam performance test, determination of surface tension and infrared spectrum.The results of pure mineral test show that OP series surfactants had good synergistic effect on sodium oleate, the best synergistic agents are OP-10, OP-12, OP-15, and the best compound ratio is 1∶4-1∶9.The preliminary study of Qingping phosphate ore shows that the yield of fine mineral could be effectively increased by nearly 10% and the concentrate grade could not be effectively increased with the compound the ratio of OP-10, OP-12, OP-15 and MX-135 is 1∶9.The results of foam performance test and surface tension test show that the synergistic effect of OP series surfactants is mainly due to its solubilizing effect and had little correlation with its foaming ability.Infrared spectrum show that the essence of OP series surfactant is its solubilization, which can effectively promote the adsorption of sodium oleate on the surface of apatite.