This paper presents the method by which the change of abrasive grit size and the silicon particle size of multiwire saw slurry are measured quantitatively. The mechanism of wire saw slicing is discussed from a microscopic viewpoint based on the measurement results ; (1) GC abrasives and silicon particles are separated each other by the suction filtering and chemical treatment technique. Their size distributions are measured by Coulter counter with 10% accuracy. (2) After slicing a 400mm-diameter ingot with 200mm in length, the consumed abrasives are estimated to be approx. 7.0% in mass and 2.4% in number. On the other hand, silicon particles generated by the slicing range in 1-10μ m diameter. (3) It is presumed as one of microscopic models of wire saw slicing that an indentation, a rolling and a scratching are actions of abrasives, and an effect of the scratching grows as the wire running speed increases.