The invention fine/slurry coal slime auto cleaning technique and its device is most adaptive to cleaning the mixture of coal slurry and water in water bin in mines. By applying extracting, buffering, dehydrating, loading and other method, adopting the devices needed at each process, controlling with switches, the auto cleaning of coal slime in water bin in mines is acquired, removing the tough task of cleaning the water bin by human power, improving the piling enviorment, while lowering the number of new water bin needed, improving the general economic performance, moreover protecting the environment. Its device is rational adopted, and of long service life, time and power saving, and highly practical.