The application of PCE-11 as a modifier in the flotation separation of brucite and serpentine relates to the field of brucitebeneficiation and purification technology. This invention provides a flotation separation method for brucite and serpentine using PCE-11 as a modifier. By introducing PCE-11, the difference in floatability between brucite and serpentine during flotation is amplified, achieving effective separation of brucite and the gangue mineral serpentine. This invention has advantages such as high efficiency, low cost, no pollution, and simple process.