“理化检验通讯”63年第七期刊登的“金属拉力试验断面收缩率(ψ%)的计算尺法”一文,看来计算速度上可提高,但其精确度达不到规定要求,因为没有考虑加工公差。我们按加工公差计算了几种不同直径的试样,当收缩率在15～60%左右时,直径5(±0.1)毫米时,误差为±1.5至13.5;直径8(±0.1)毫米时 “Physical and chemical testing communications ” published in the seventh issue of 63 “metal tensile test section shrinkage (ψ%) calculation rule ” article, it seems the calculation speed can be increased, but the accuracy of less than the provisions Requirements, because did not consider the processing tolerances. We calculated by process tolerance several different diameter samples, when the shrinkage rate of about 15 to 60% diameter of 5 (± 0.1) mm, the error is ± 1.5 to 13.5; diameter of 8 (± 0.1) mm