<p>This study examines the impact of harsh parenting by fathers and mothers on the internalizing problems of vocational college students, exploring the mediating role of psychological flexibility and the moderating role of interpersonal emotion regulation. A sample of 2177 vocational college students was surveyed using the Harsh Parenting Questionnaire, the Avoidance and Fusion Questionnaire for Youth, the Interpersonal Emotion Regulation Questionnaire, and the Depression Anxiety Stress Scale. The findings indicate that: (1) both father’s and mother’s harsh parenting significantly predicts internalizing problems in vocational college students; (2) psychological flexibility fully mediates the relationship between father’s harsh parenting and internalizing problems and partially mediates the relationship between mother’s harsh parenting and internalizing problems; (3) interpersonal emotion regulation moderates the effects of father’s harsh parenting and psychological flexibility on internalizing problems, and also moderates the effect of psychological flexibility on internalizing problems, with higher levels of interpersonal emotion regulation weakening these predictive effects. These results suggest that enhancing psychological flexibility and interpersonal emotion regulation can help mitigate the adverse effects of harsh parenting, providing valuable insights for the development of targeted interventions to support the mental health and well-being of vocational college students.</p>