The invention discloses a combined inhibitor for inhibiting talc and other easy-floating gangue minerals and a using method of the combined inhibitor and relates to the inhibitor for molybdenum ores or molybdenum associated ores, especially the molybdenum ores (molybdenum associated ores) containing the easy-floating gangue minerals such as talc, mica, calcite and chlorite and the using method ofthe inhibitor. According to the flotation method for separating molybdenite from the easy-floating gangue minerals such as talc, mica, calcite and chlorite by using the combined inhibitor, in a neutral or weakly alkaline state of ore pulp, kerosene or diesel oil is used as a collector, an inhibitor solution formed by mixing Na2SiO3 and CD in a ratio of 1:1 to 1:3 is used, and flotation is carriedout on the molybdenum ores, wherein CD is formed by mixing, by mass percentage, 30-60% of aluminum sulfate, 10-20% of dextrin and 20-40% of carboxymethyl cellulose (CMC); the combined inhibitor is 400-1,000 g/t, and the amount of collector kerosene or diesel oil or transformer oil is 50-200 g/t; and the ores are the molybdenum ores containing the easy-floating gangue minerals such as talc, mica, calcite and chlorite or molybdenum associated ores containing the easy-floating gangue minerals such as talc, mica, calcite and chlorite.