The purpose of this study is to confirm whether the defining vocabulary of particles and endings in Korean Basic Dictionary is controlled and to propose an improvement so that can help Korean learners understanding. To this end, 357 definitions of particles and 757 definitions of endings were examined. In addition, it was compared and determined whether defining vocabulary used only once was properly used. As a result, 76 out of about 388 defining vocabulary of particles were used once. Among them, nouns accounted for the highest percentage with 37, followed by low-frequency vocabulary in the order of verbs, adjectives, adverbs, adnominals, connective endings, suffix, auxiliary particle. And 70 out of about 570 defining vocabulary of endings were used once. Also, nouns accounted for the highest percentage with 26, followed by low-frequency vocabulary in the order of verbs, adjectives, adverbs, auxiliary adjectives, connective endings, auxiliary verb, auxiliary particle, numeral. In this paper, in the case where it is determined that modification is necessary among low-frequency vocabulary, Standard Korean Language Dictionary, Korea University Korean Dictionary, Sejong Corpus were analyzed together and suggested improvement.