Experimental and numerical studies have been conducted on the effect of blade angle in a mechanical impact mill. The particle trajectories around the rotor were calculated for a long simulation time by use of the CFD software Fluent and were compared with the experimental results obtained previously The product fineness was related to the amount of normal impact energy of particles colliding with the blade and stator walls while the particles pass through the pulverizing zone. It was found that fine particles with a narrow range of size distribution are obtained when blades are inclined forwards at an angle of 30 degrees.