BACKGROUND: Athletic fatigue is an inescapable issue in competitive sports. It belongs to a physiological response that is triggered when competitive athletes are trained to a critical point. OBJECTIVE: The study aims to explore the relationships involving boxers’ social support, mental fatigue, coach leadership behaviors and psychological resilience. METHODS: 1050 boxers were selected in several provinces across China and investigated on the basis of the Social Support Questionnaire for Athletes, Mental Fatigue Scale, Psychological Resilience Scale, and Leadership Scale for Sport. RESULTS: Boxers’ social support was negatively correlated with mental fatigue and psychological resilience, while it was positively correlated with coach leadership behaviors. Apart from direct effects on mental fatigue, other impacts are imposed by boxers’ social support via mediating effects such as coach leadership behaviors and psychological resilience. The total effect value was -0.18, the direct effect value was -0.08, and the indirect effect value was -0.12; furthermore, coach leadership behaviors and psychological resilience play a mediating role, accounting for 65.57% of the total. CONCLUSION: In order to alleviate the stress from intense competitive training and abate mental fatigue, competitive athletes may be encouraged in subsequent training to seek all-sided social support for social interpersonal relationships. While clarifying the mechanism how the external environment affects individuals, this paper explains the principle of social support on athletes’ psychological fatigue and identifies mutual influences between coaches and athletes.