Abstract: In order to solve a series of industrial production problems of storage, transport and dehydration of coal flotation concentrate caused by the strong stability of their foam, the defoaming experiments of silicone defoamer (G) and emulsified hydrocarbon oil defoamer (R) for flotation concentrate were studied to revel the effect of the adding method and dosage of defoamer on the defoaming results. In addition, the effect of residual defoamer in circulating water on flotation process was revealed by the flotation test. The results showed that the rate and degree of defoaming can be increased more effectively by defoamers added in the way of spraying. The defoaming property is better with the increase of the dosage of defoamers and the silicone defoamer is superior to emulsified hydrocarbon oil defoamer. A low amount of defoamer in circulating water has little effect on flotation. When the residual amount increasing, silicone oil defoaming agent reduces flotation selectivity and inhibits flotation, while emulsified hydrocarbon oil defoamer can promote it. It is suggested that the flotation concentrate should be defoamed with low dosage emulsified hydrocarbon oil by spraying.