To clarify the significant revision of the new version international accuracy standard of the standard ISO 1328- 1: 2013（ E） based on the principles and frames of the old version of the standard ISO 1328- 1: 1995. The difference between two versions of ISO 1328- 1 is compared,including the definition and evaluation method of accuracy level,applications range,and elemental deviations（ pitch,profile,helix）,and measurement items and the number of teeth. Especially the tolerance value calculated through the formula in the new standard and the allowable values provided in the list table of the old one is compared and analyzed. The changes can be found from the results as follows: the accuracy level range is from 1 to 11 in new standard,pitch circle diameter d increase to 15 000 mm and tooth width b increase to 1 200 mm respectively in applications,the form and slope deviations are the compulsory measurement items,the regulation of the minimum number of teeth measured are added in,the definition and evaluation method of the elemental deviations are revised,the big difference can be found between the tolerance value of elemental deviations in new standard and permissible value given in the list in old one,which is dozens of micron at 5 grade of accuracy level,and hundreds of microns at 11 grade of accuracy. There is no doubt that big difference exist between the two versions of the cylindrical gear accuracy standard,which has changed the basis of the accuracy evaluation of the gear elemental deviations and will contribute to a series of revision of other related standards. More attentions should be paid by someone involved including standard development,gear measurement instrument design and gear quality management.