This study was conducted to develop a word fluency diagnostic tool as part of the basic literacy diagnostic tool development. In the work itself, a theoretical basis for words for fluency diagnosis was established, focusing on the meaning of vocabulary and phonological recognition, a test was designed through several meetings with Korean language education experts, while preliminary test and a main test were conducted to diagnose fluency. Item validation and diagnostic level setting were also performed. At this time, the theoretical background for selecting words for diagnosing fluency was carefully reviewed to derive the principle of word selection, and among the various methods available to stimulate phonological awareness, we focused on the phonological environment, especially the hierarchy of phonological variability, rather than the quantitative hierarchy centered on the number of syllables. Indeed, it can be said that the special characteristic of this study is its setup and the fact that the words to be tested were justified by conducting the main test with schools nationwide. The tool developed in this study is expected to be highly applicable to the school field in that teachers can directly evaluate students on a one-to-one basis and immediately diagnose word fluency.