The purpose of this study was to find out how phonological awareness-based Hanguel reading intervention affected the decoding ability of students in the at-risk of dyslexia. The subjects of this study were three 2nd grade students and one 3rd grade student at-risk of dyslexia attending elementary school. This study adapted multiple-probe design across subjects. Phonological awareness-based Hangeul reading intervention was structured so that students could master the corresponding skills between letters and sounds based on phonological awareness activities in consideration of the scientific and economical characteristics of Hangeul, and the content validity was verified and modified and developed. The intervention was conducted three times a week, 40 minutes per session, for a total of 40 sessions, one-on-one with one researcher. As a result of the study, all four subjects confirmed a positive change in decoding ability in the intervention section compared to the baseline section, and showed a statistically significant improvement. And it was confirmed that the effect was continued through the maintenance test. In addition, it was confirmed that there was a clear difference in the improvement speed of decoding ability and the degree of acquisition by function. This study presented a discussion of the study results, limitations, and suggestions for follow-up studies.