Purpose: The purpose of this study was to identify the influencing factors of oral environment and self-care behavior on the oral health-related quality of life in the elderly with diabetes. Methods: The participants were 110 elderly patients with diabetes and follow- up care on their outpatient clinic in D and G city. Data were collected September-December 2018, using questionnaires of the Oral Health Impact Profile (OHIP-49) and Kim’s Self-care Behavior, measuring with the tooth-pick (Premiers Dental), Halitosis Checker (HC-212M), and Moisture Checker for Mucus (MCM) for oral environments. The data were analyzed the by independent t-test, oneway ANOVA, Pearson’s correlation, and stepwise multiple regression analysis using an IBM SPSS Statistics 25.0 Program. Results: There was positive correlation between oral health-related quality of life and self-care behavior (r=.61, p<.001), negative correlations among halitosis (r=-.34, p<.001), gingival index (r=-.31, p=.001) and plaque index (r=-.32, p=.001). Self-care behavior (β=.46, p<.001), subjective health status (good) (β=.23, p=.002), halitosis (β=-.16, p=.030), and plaque index (β=-.15, p=.041) explained 46.0% of the variance in the oral health-related quality of life. Conclusion: It is necessary to develop nursing care for elderly patients with diabetes that can enhance the self-care behavior and subjective health status, and lower halitosis and plaque index, the factors influencing the oral health-related quality of life in elderly patients with diabetes