Objective: This study aimed to develop and apply the home connection program for promoting the mathematical interaction of parents of 3-year-olds. Methods: We surveyed questionnaires for 36 parents and interviewed 3 parents of 3-year-olds for the development of the program. Twenty-one 3-year-olds were selected as participants in the program. Quantitative data from a checklist for parent s mathematical interaction were analyzed using repeated measures ANOVA. Qualitative data from self-evaluation of teachers and parents were categorized and analyzed in terms of meaning. Results: Based on the home connection program, the session were provided in the following order [educare center activities ➠ home-linked activities ➠ home+educare integrated activities] and in each session, the three-step course [sharing of thinking ➠ gathering of thinking ➠ broadening of thinking] was applied. Implementation of this program led to promoting parental mathematical interaction. Conclusion/Implications: This study will lead to follow-up studies that reveal positive effects of our program.