Abstract: In order to overcome the difficulties in treating the coal slime water, a general check-up and study of the washing processes is conducted according to coal preparation related national or industrial standards. It is found through the study that the irrational application of equipment and processes of heavy medium or coal slurry treatment system is the source of the long-standing troubles besetting the plant′s flotation system. In line with the actual specific conditions of the plant, a series of targeted improvement measures are adopted as follows: optimization of spray system of medium draining screen, reform of arrangement of the chute at the inlet end of the desliming screen, and improvement of shaft sealing water system, for reducing water consumption, optimizing slime water treatment system, eliminating or dramatically reducing any inappropriate process cycle and controlling flotation feed pulp density within a reasonable range with the aid of some complementary measures. Practice shows that the renovation work has made it possible for the plant to improve flotation efficiency, lift restriction on capping the capacity of heavy medium washing system, ease the load on slime water treatment system, ensure the reliable and smooth operation of overall washing systems.