The negative effect of work-leisure conflict has attracted the attention of researchers. However, no previous research has determined the relationship between work-leisure conflict and ego depletion. Therefore, this study explores the relationship between daily work-leisure conflict and ego depletion, as well as the role of individuals’ negative emotions and core self-evaluations in this process based on ego depletion theory. Through the method of daily diary research, 77 employees were tracked for 7 consecutive work days. The results show that work-leisure conflict is positively related to employee ego depletion, that the negative emotions play a mediating role in this relationship and that core self-evaluations moderate the indirect effect of work-leisure conflict on ego depletion through negative emotions. In this study, daily diary method is used to verify the dynamic characteristics of work-leisure conflict, negative emotions and ego depletion, and some new insights into how to reduce employee ego depletion are provided.