This study used a questionnaire survey method to investigate the effect of perception of excessive competition on the pos? itive mental well - being of 627 Chinese college students, as well as its internal mechanism and boundary conditions through a 5 - month two - stage longitudinal follow - up study. The results show that the perception of excessive competition negatively predicts the mental well - being of college students, and the self - regulatory fatigue plays an intermediary role between the perception of excessive competition and mental well - being, furthermore, the self - regulatory fatigue and the positive mental health have a mutual prediction effect; at the same time, self - concept clarity moderates the effects of perception of excessive competition on self - regulatory fatigue and mental well - being. This study provides a theoretical basis for the intervention of college students’ mental well - being under the environment of excessive competition in higher education, and emphasizes the importance of college students to actively coping with ex? cessive competition pressure, developing clear self - concept, and protecting self - regulation resources.