Abstract: The flip-flow screen has a series of merits such as high screening efficiency and handing capacity,low power consumption,noise and dynamic load,its screen aperture is not easy to jam.There were lots of problems in Guojiawan coal preparation plant,the slime water processing system was overloaded,the slack coal processing system was unstable,the upgrading effects wasn’t obvious,the viscosity of slime was high.Based on the coal qualities,provide four kinds of preparation methods,which are complete washing,50 percent slack coal washing,fines removal with 6 mm flip-flow screen,fines removal with 3 mm flip-flow screen.The analysis of productivity and economic benefits of these four methods show that,the third method can decrease the raw coal feed,processing cost and slime productivity,increase the system stability.So choose the third method to optimize Guojiawan coal preparation plant.