Abstract: The sulphidizing−amination method is one of the main beneficiation methods for sphalerite ore, which has good indexes in industrial production, but there is a problem that the flotation foam is sticky and difficult to defoam. The performance of two−phase and three−phase foams in sphalerite flotation using sulphidizing−amination method, and the effects of sodium sulfide dosage, dodecylamine dosage, mineral content, mineral particle size, mineral type, etc. on foam stability were studied. The pulp viscosity of different mineral contents was investigated at last. The results show that in the sulphidizing−amination flotation of sphalerite, sodium sulfide can improve the stability of two−phase and three−phase foam. Mineral particles of different sizes have different effects on foam stability. Adding sphalerite and quartz particles with a particle size of −74+37 μm can reduce foam stability, while adding sphalerite and quartz particles with a particle size of −37 μm can improve foam stability. The −18 μm quartz particles have a particularly significant effect. When dodecylamine co−existed with micro−fine quartz, the flotation foam was particularly stable. The half−life of the three−phase foam after the addition of quartz particles is higher than that of sphalerite, because the viscosity of quartz pulp is higher than that of sphalerite, so the Marangoni effect of the foam film is enhanced, resulting in a slower drainage rate, a slower thinning rate of the foam film, and stronger foam stability.