Abstract: The problem facing the Longhua Coal Preparation Plant is that the coarse coal treated contains an excessive proportion of mixed small coal, which is liable to exceed the limit in calorific value and moisture. For tackling this problem, under the prerequisite of ensuring that only limited effect is imposed on undersize fraction of small sized coal, the scheme for reducing mixed small coal yield is proposed in line with the specific conditions of the plant. The scheme proposed involves diminishing the size of the hole on upper deck of cleaned coarse coal medium draining screen and moving backward the medium draining screen's water-spraying pipe. Practice shows while ensuring the products are up to the required standards in moisture and calorific value, the yield of mixed small coal is reduced by a level of up to 30-40 t/h, bringing about an additional revenue of over 10 million yuan for the plant.