In order to understand Xǔ Shèn’s 許慎 contribution to the analysis of the Chinese writing system, it is important to clarify the terminology he uses in his Shuōwén jiězì 說文解字 (100 AD). In this paper I shall focus on the term shěng 省. Scholars who have studied the problem of shěng 省 in Shuōwén usually tried to reveal the mistakes either made by Xǔ Shèn or added later to the text, from different perspectives including the classification of the graphs in traditional liùshū approach, paleography, as well as phonological reconstructions. i Most of these authors may be right in their critical investigation of shěng 省, there are indeed many mistakes in Xǔ Shèn’s graphic analysis, but none of them considered the problem as a whole or tried to understand what was the real reason for Xǔ Shèn to use this term. Shěng 省is a rather complex term with different significations, such as ommission, abbreviation, fusion, etc. I shall first clarify the meanings and uses of shěng in Shuōwén, before trying to understand why Xǔ Shèn needed this special term. We will see that despite many mistaken graphic analysis, already described by Chēn Shìhuī 陳世輝 (1979), Qiú Xīguī 裘錫圭 (1988), and others, shěng 省was an important tool for Xǔ Shèn’s methodological approach to the Chinese writing system that also shows his deep knowledge of the evolution of the script.