The invention provides a phyllosilicate mineral depressor for sulfide ore floatation and a preparation method thereof. The phyllosilicate mineral depressor for the sulfide ore floatation is prepared from the following components in part by weight: 0 to 20 parts of modified corn starch, 8 to 30 parts of sodium alginate, 1 to 35 parts of carboxymethyl cellulose or polyanionic cellulose or methylenenapadisilate dinaphthalene sulfonate, and 5 to 55 parts of sodium hexametaphosphate. The preparation method comprises the following steps of: selecting the reagents according to types of depressed minerals; adding the reagents in a high-speed mixing granulator in the set ratio for granulation; and drying the obtained grains to obtain the phyllosilicate mineral depressor for the sulfide ore floatation. The product has the characteristics of small dosage, good depression selectivity, low toxicity, and the like. The specific depressor is mainly applied to depressing phyllosilicate minerals such as talcs, serpentines, chlorites, kaolinites and the like during the sulfide ore floatation, thus the specific depressor is favorable for improving floatation concentrate grade and metal recovery rate, and is particularly suitable for floating talc-containing molybdenites and nickel sulfide ores.