Against the backdrop of delayed marriage, increasing singlehood, and the growing prevalence of overtime work, understanding how overtime work shapes young adults' marital decisions has become an issue of both academic and policy importance. This study examines the relationship between overtime working hours and marriage intention, as well as the underlying mechanisms, using data from the 2023 “Specialized Survey on Delayed marriage, Childlessness or Delayed childbearing, and Low fertility Groups” conducted by Renmin University of China. Focusing on unmarried individuals aged 30-49 who engage in overtime work, this paper employs ordered logit models to explore the nonlinear association between overtime working hours and marriage intention.

The results reveal a significant inverted U-shaped relationship between overtime working hours and marriage intention.A moderate level of overtime is associated with higher marriage intention, whereas excessive overtime significantly suppresses individuals' willingness to marry. This finding suggests that the impact of overtime work on marriage intention is not linear but varies by the degree of overtime exposure. Mechanism analysis, grounded in the work-family conflict theory and work-family enrichment theory, shows that overtime work exerts dual and competing influences. On the one hand, excessive overtime increases health pressure and strengthens the salience of work-role identity, both of which crowd out individuals' capacity and willingness to assume family roles. This reflects the work-family conflict effect. On the other hand, overtime work increases individual income, which enhances economic resources and strengthens individuals' bargaining power in the marriage market, thereby raising marriage intention. This reflects the work-family enrichment effect. The empirical results confirm that health pressure, identity salience, and individual income serve as important pathways linking overtime working hours and marriage intention.

Heterogeneity analysis further reveals contextual and gender differences. The inverted U-shaped relationship is statistically significant in non-first-tier cities but not in first-tier cities, possibly because overtime work has become normalized in major metropolitan areas,thereby reducing variation in overtime exposure and individuals' sensitivity to it. In addition, excessive overtime significantly suppresses marriage intention among unmarried women, while the inhibitory effect is not statistically significant among men. This finding is consistent with gender role expectations and the greater work-family conflict typically experienced by women.

This study contributes to the literature in several ways. First, it identifies the nonlinear effect of overtime working hours on marriage intention, offering new empirical evidence on how work time allocation influences marital decisions. Second, by focusing exclusively on individuals who actually engage in overtime work, the study avoids confounding effects from those without overtime exposure and more precisely captures the difference between moderate and excessive overtime. Third, by simultaneously testing the mechanisms of health pressure, identity salience, and individual income, the paper integrates the work-family conflict and enrichment perspectives into a unified explanatory framework. Finally, the findings provide policy implications for promoting work-family balance, improving labor protection, and designing differentiated marriage and family support policies across regions and genders, thereby contributing to sustainable demographic, social, and economic development goals.