Abstract: To improve classification and separation effect of coal slurry in Sanjiaohe mine coal preparation plant,modification on coal slurry system was made by a series of measures,such as strengthening production management of raw coal desliming screen,adjusting parameters of classification cyclone or mesh of vibrating sieve bend,adding spray water on vibrating sieve bend etc. The application shows that feeding content of + 1mm into classification cyclone is reduced 4. 89%; efficiency of classification is raised 11. 08% at the same time coal slime recovery of + 0. 25 mm and fine slime removal of-0. 074 mm are improved,which has increased yield of clean coal as well as reduced feeding volume into flotation and consumption of agent.