Previous research has identified the crossover of burnout among spouses or colleagues in workplaces, but little is known about how burnout crosses over from one student to another. This two-wave longitudinal study examined the mediating effects of changes in academic self-efficacy and value in the crossover of burnout among adolescent students based on the Expectancy-Value Theory. Data were collected from 2346 Chinese high school students (Mage = 15.60, S = 0.82; 44.16% boys) over a period of 3 months. The results reveal that after controlling for T1 student burnout, T1 friend burnout negatively predicts T1-T2 changes in academic self-efficacy and value (intrinsic value, attachment value, and utility value), which in turn negatively predict T2 student burnout. Thus, changes in academic self-efficacy and value completely mediate the crossover of burnout among adolescent students. These findings highlight the importance of taking into account the decline of academic motivation in understanding the crossover of burnout.