Abstract: The proportion of raw coal treated and clean coal production capacity are both low at Lijiahao Mine Coal Preparation Plant. To reverse this situation,the flip-flop screen is selected for use for its special merits of being high in efficiency,low in energy consumption and noise level and convenient in maintenance,and its screen surface is not easy to get clogged up. Work is made on the technical renovation of the screen to enable it to screen at a size of 6 mm. practice shows that for treating the raw coal with the same property,the yield of clean coal is increased to 45%,a grouth of 12% and the yield of blended coal is lowered to 37%,a drop of 17%,well meeting the expected result.