Abstract: Sodium sulfide is an important regulator with a wide range of application in the flotation. It can act as depressant, reagent removal agent and activator in processing non-ferrous metal sulfide, while as important vulcanizing agent in non -ferrous metal oxide ores. In the electrochemistry of flotation solution, it can adjust the pH and Eh of slurry. By combining practical application with basic properties of sodium sulfide, this paper discusses its different functions and mechanisms in flotation, and points out that the key to its reasonable use is to control its dosage and action period.