《下学集》是日本室町时代的“国語辞書”，其收錄的詞語分为：天地門、時節門、神祇門、人倫門、官位門、人名門、家屋門、気形門、支體門、態芸門、絹布門、飲食門、器財門、草木門、彩色門、數量門、言辭門、畳字門共十八個門類。元和三年版的《下學集》共有單字總數3083字，都用漢字記載，并在漢字旁邊用片假名標注讀音，有的會加上漢語的釋義。本文簡單介紹日本漢字的使用情況，详细叙述了《下學集》的成書、版本、編纂內容及其特点，梳理了國內外對日本辭書以及對《下學集》的研究成果。特别梳理了國字的研究歷史，對國字進行了分類，擴展了國字的內容。最后将《下學集》的文字进行分類整理，以《下學集》的收字為例，分類考證其收字與漢籍漢字之間的異同，說明每一類字的情況。總結了《下學集》的收字特點。

The Japanese Dictionary "KaGakuSyuU" is the "National Language Dictionary" of Japan's Muromachi era. There are a total of 18 categories of state-of-the-art,, food, education, grass, wood, color, number, language, and so on. KaGakuSyuU edited in the 3rd year of YuanHe collected 3,083 words,they are all recorded in Chinese characters and are marked with katakana characters next to the Chinese characters.,some of them added interpretations in Chinese. This article briefly introduces the use of Japanese Kanji, describes in detail the book completion, edition、content of the book and clarifies the research results of the Japanese dictionary at home and abroad as well as the study of the next book. In particular, the research history of Kokuji was combed, the Chinese characters were classified, and the content of Kokuji was expanded. In the end, this paper concluded the features of “KaGakuSyuU” word collection.