Mental health problems among college students are increasingly prominent. The negative effects of emotional distress on college students' mental health have been supported empirically. It is important to understand the psychological processes underlying this relationship. Using a longitudinal design, the present study aimed to reveal the explanatory mechanism of the association between dimensions of dispositional mindfulness and mental health problems among Chinese college students by testing the mediating effects of experiential avoidance and intolerance of uncertainty. A total of 907 Chinese college students (57% male; Mage = 20.33 years) were invited to complete self-report questionnaires at two time points. Mindful awareness, acceptance and mental health problems (depression, anxiety and stress) were assessed at baseline (T0). Experiential avoidance, intolerance of uncertainty and mental health problems were assessed at the 6 month follow-up (T1). Following structural equation modeling (SEM) analyses, the results show that high levels of mindful awareness and acceptance may diminish mental health problems by decreasing the levels of experiential avoidance among college students. However, only mindful acceptance diminished mental health problems through decreased intolerance of uncertainty. In addition, our study found that mindful awareness and acceptance may have different functions when working alone. Specifically, these two constructs may have different relationships with mental health. Identifying these mechanisms by which dispositional mindfulness is associated with college students' mental health over time has potential value for the prevention of potential mental health issues and timely interventions.