《龍龕手鑑》，原名《龍龕手鏡》，凡四卷，是遼代僧人釋行均為佛徒通解文字、正定字形、注音釋義，俾研讀佛典、透析佛理而編纂的一部佛學字書。此書收字二萬六千餘字，在編纂體例方面，《龍龕手鑑》以「字形部首」統攝二萬六千餘字，其部首之序，按平上去入四聲為次，計平聲九十七部，上聲六十部，去聲二十六部，入聲五十九部，合計二百四十二部首。就分部編次上，行均不囿於東漢許慎《說文解字》「據形繫聯」、「始一終亥」的體例，而按當時通行俗體以四聲排列。體例雖不盡然完善，但頗具有創新的精神。 本文撰作之目的，便是要藉由對《龍龕手鑑》的部首型態之分析，了解今日通行字典部首嬗變之源流始末，並強調《龍龕手鑑》一書在字典部首演變史中的過渡地位。

“Long-Kan-Shou-Jian”, the original name is “Long-Kan-Shou-Jing”, consists of four volumes. It is edited by the monk of Liao dynasty, Shi-Xing-Jun, who elucidated the characters, corrected the morphology, studied the phonetic notation, and translated the meanings to help all the monks to interpret Buddha’s principle thoroughly. The book collects over twenty six thousand words based on the classification of morphology. He used the rule of four tones, level tone, falling-rising tone, falling tone, and entering tone to order the radical of this book. It collects ninety seven volumes of level tone, sixty volumes of falling-rising tone, twenty six volumes of falling tone, and fifty nine volumes of entering tone. All of these are two hundred and forty two volumes. Xing-Jun’s study was not limited on the regulation of East Han dynasty, Xu-Shen’s “Shor-Wen-Jei-Zi”, which use the rule of “the relationship of morphology” and “begin from one and end at Hai”. He arranged the sequence based on the general rule of four ones. Although the style of “Long-Kan-Shou-Jian” is not perfect but it possesses the spirit of innovation. The goal of this article is to understand the original development and the evolution of the current dictionary after we analyze the radical morphology of “Long-Kan-Shou-Jian”. At the same time we emphasize the transition status of the radical evolution of dictionary.