Abstract: The paper introduced the determination of key parameters and optimization design of the XJM-S45 flotation machine,and its structure features such as double froth skimming,the aeration and agent adding designed in one tube and inside and outside flanges joint connected.The commercial application result of XJM-S45 flotation machine（two cells） in Dayangquan colliery coal preparation plant shows that the design of the machine is reasonable,the performance is better so it meet the production requirement of the plant.The pulp feed is 850-1 200 m³/h,the unit treating capacity of pulp is 9.4-12.2 m³/（m³·h）,which reached the design expected.