Abstract: In order to solve the problems of low yield and high ash content of clean coal in flotation system in Qianjiaying coal preparation plant,taken the renovation on the process and equipment that do not adapt to development of production.Based on the analysis of sieving,float-and-sink and floatability tests,determined flexible technology flowsheet,and utilized the advanced processed of multi-separation and sized flotation,and at same time also used big sized flotation and de-watering devices in the renovation.After the renovation of flotation system,the yield of clean coal and ash content of tailings both increased in that coal preparation plant.