Abstract: According to the problems of low cabin pressure,long discharge cycle and higher water content of flotation clean coal of pressure filter in flotation system,take the measures of bettering size characteristics of feed,improving the cabin pressure and discharge cycle to reduce the water content of clean coal.The results showed that when the opening degree of coarse particle adding valve is 10%,velocity of main shaft is 0.85 r/min,cabin pressure increased from below 180 kpa to more than 220 kpa,and the discharge cycle shortened from 300 s to 240 s,the water content of flotation clean coal reduced below 18%,and also solved the problem of the run out of flotation clean coal pool.