許慎為《說文》立五百四十部首，學者蔡信發先生<說文部首正補釋例>一文對五百四十部首或增補或省併而釋其例，本文僅對其中部首「省併」部分持保留態度，試從許慎立部原意探討說明，以為參考。

　　　　　Hsu Shen established 540 radicals of Chinese characters in The Shuo-Wen. Later, Mr. Tsai Hsin-fa made several additions to and deletions from these 540 radicals in his paper The Rules for Additions and Deletions on The Shuo-Wen Radicals'. This essay aims at exploring the rules for additions and deletions on radicals while retaining a reserved attitude, and tries to approach Hsu shen's motive behind establishing the 540 radicals.