To explore the relationships among major identity, academic emotions and university students’ depression, a total of 329 subjects completed the College Students’ Speciality Identity Questionnaire, the Adolescent Academic Emotions Questionnaire, and the Self-Rating Depression Scale. Results showed that: 1) major identity negatively predicated depression in university students; 2)major identity positively predicated the positive academic emotions, but only negatively predicated negative-low arousal academic emotion; 3) positive-low arousal and negative-low arousal academic emotions played full mediating roles between major identity and university students’ depression. Therefore, it can be concluded that the influence of major identity on university students’ depression is a kind of boiling frog effect by its nature.