Abstract: A method and a system for preparation of a highly concentrated and fine-grained suspension such as a coal-water slurry comprises feeding of coarse solid matter by a metering conveyor type weigher and of a carrier liquid and additives into a ball mill, in which the solid matter is ground and the suspension is formed. The particle size and distribution are analyzed and the viscosity is determined. The speed of the ball mill and the amounts of the carrier liquid and additives are adjusted during the continuous preparation process so that a suspension with constant characteristic features such as particle size and distribution, content of solid matter and viscosity is supplied into a pipeline.