The aim of the present study was to investigate the mediating role of psychological well-being in the relationship between work-family conflict and fertility motivation in private sector employees.The present study is applied in terms of its purpose and descriptive-correlational in terms of its nature and method. Also, in order to examine the relationships between research variables, the structural equation modeling method was used. The statistical population of this study consisted of employees working in factories and private sector organizations in Karaj in 1404. Finally, after considering the entry and exit criteria, 369 people were selected using the convenience sampling method. The research instruments included; Carlson et al.'s Work-Family Conflict Questionnaire (2000), Nakhai and Khajeh's Influencing Motives on Childbearing Intention Questionnaire (1401),and the Riff 18-item Short Scale of Psychological Well-being (1989). The findings of the study indicated that work-family conflict had a negative and significant relationship with psychological well-being (β = -0.61, p = 0.001) and fertility motivation (β = -0.35, p = 0.001).Also, the relationship between psychological well-being and fertility motivation was direct and significant (β = 0.58, p = 0.001).In addition, this study confirmed the mediating role of psychological well-being in the relationship between work-family conflict and fertility motivation (β = -0.295, p = 0.003). Accordingly, it is hoped that, considering the results of this study, policymakers and planners in the field of family and employment will provide the basis for strengthening fertility motivation by designing supportive interventions to reduce work-family conflict and promote the psychological well-being of employees.