Objective To explore the effect of learning burnout on subjective well-being of military medical university students and the mediating role of psychological capital. Methods The learning burnout questionnaire, well-being scale and psychological capital scale were used to survey 796 military medical university students. The correlation of subjective well-being and psychological capital with learning bornout was analyzed. A intermediary function equation was established and the mediating effect of psychological capital was tested. Results The subjective well-being score of military medical university students was 4.42±0.77, psychological capital scale score was 4.48±0.67, and learning burnout score was 2.45±0.69. The subjective well-being, psychological capital and learning burnout scores were different among different grades, the subjective well-being scale and psychological capital scale scores of freshmen were significantly higher, and the learning burnout score was significantly lower than those of the junior students (t_{subjective well-being}=12.45, P<0.01; t_{psychological capital}=6.01, P<0.01; and t_{learning burnout}=-13.96, P<0.01). The learning burnout was negatively related to the subjective well-being and the psychological capital (r=-0.539, P<0.01, and r=-0.721, P<0.01). The psychological capital was positively related to the subjective well-being (r=0.596, P<0.01). The psychological capital had a partial mediating effect between learning burnout and subjective well-being, and the proportion of the mediating effect of total effect was 57.90%. Conclusion The subjective well-being not only can directly predict learning burnout of the students in military medical universities, but also indirectly predict the learning burnout through psychological capital. Improving subjective well-being of military medical university students is helpful for alleviating the learning burnout, and the mediating role of psychological capital should be emphasized at the same time.