The current study investigated the developmental trajectories of academic burnout and test anxiety, alongside the relationship between these constructs and the moderating effect of perfectionistic concern over mistakes, employing latent growth curve model. A total of 427 Chinese adolescent students completed the Adolescent Student Burnout Inventory, which assesses three dimensions--emotional exhaustion, cynicism, and inefficacy--along with the unidimensional Test Anxiety Inventory. Data were collected at three measurement points, approximately 2-month apart, spanning the start to the end of the spring semester. Also, they reported their levels of perfectionistic concern over mistakes at the study's onset. Findings indicated that emotional exhaustion, cynicism, and test anxiety increased from T1 to T3, while inefficacy decreased across the same timeframe. Furthermore, the initial levels and changes in the three academic burnout dimensions were significantly correlated with the initial levels and changes in test anxiety. Notably, only the initial levels of emotional exhaustion were predictive of subsequent changes in test anxiety, i.e., higher levels of emotional exhaustion at the beginning of the semester predicted a faster increase in test anxiety over the semester. Finally, perfectionistic concern over mistakes moderated the relationships between the initial levels of emotional exhaustion and test anxiety, and between the initial levels of the three academic burnout dimensions and subsequent changes in test anxiety. This research contributes to the theoretical understanding of the longitudinal dynamics between academic burnout and test anxiety and its boundary condition. It also provides valuable implications for educational interventions within the Chinese context.