Abstract: An improved knife grinder is desinged to have a motor transmission axle which transmits one or two units of wheel axle with its angles which are facing one another and entend slightly upward and outward. A base is fixed onto the vertical bottom surface which extends from the wheel shaft in coordination with the bearing positioning wheel axle, onto the upper end of which an axle bush can be housed. One or two units of glaze wheel is fitted onto the outer edge of the axle bush. While a stripe column is housed onto the position which is corresponding to the axle bush at its interior. Extending outward from the glaze wheel, three layers made of such materials as plastic, foam and grinding cloth are formed. A stair face is set on the upper end of the plastic layer, into which a positioning cover can be housed, and its mutli-angled protrusive column will be housed into the axle bush positioning hole; while the multi-angled groove at the other end will allow the wheel axle to be tightly screwed by a scew nut.