This study aims to investigate the mediating role of marital family boundaries in the relationship between marital commitment and marital differentiation. The research method of this research was descriptive-correlational and the statistical population includes all married men and women in Qom. From this statistical population, 210 samples were selected by random sampling method. Adams and Jones (1997) Marital Commitment Questionnaire, Houshyari Marital Family Boundaries (2020) and Skowron and Friedlander Differentiation of Self Inventory (2003) were used to collect research data. The results were analyzed using correlation coefficient statistical methods and Baron and Kenny method using linear regression. Findings showed: a) There is a positive and significant relationship between marital commitment and external family boundaries; B) There is a significant positive relationship between marital commitment and the differentiation of spouses; C) The marital boundaries of the family as a whole play a mediating role in the relationship between self-differentiation and marital commitment. According to the research findings, in order to improve the level of marital commitment, it is necessary to consider modifying and improving marital boundaries and strengthening their differentiation.