Abstract: It is showed by analysing cutting movement of a circular saw that the part of teeth does not cut wood if a radial position error of teeth points of a circular saw blade exceeds a certain limit so that the low quality of cutted face and the short period of sharpening are obtained. The feed per tooth is very small when the rotative velocity is high and the feed speed is low so that the radial position error of teeth points has to be also very small. The error of teeth distance affects tooth point radial positions if the front and rear face of same tooth are shaped in different datum positions. The effect of eccentricity of saw blade upon tooth point radial positions may also be calculated by mathematical analysis. Some new formulas are given out in this paper.