Abstract: This paper discusses the research progress of organic depressor on pyrite flotation. The molecular structure of organic depressor of the sulfide ore is closely related to its depressing ability. The organic depressor of the sulfide ore can be divided into big molecule depressor and small molecular depressor with different features. Big molecule depressor has more close solid functional groups and hydrophilic group with bigger molecular weight, which lead to stronger depression ability on pyrite. The close solid groups of small molecule depressor often have sulfur atoms or phosphorus atoms containing several hydrophilic groups resulting in weaker depression ability. Small molecule depressors are usually used combing with other depressores to increase the depression ability on pyrite. The application and depression mechanism of different types of organic depressores on pyrite are discussed.