<p>The paper is devoted to exploring how teachers’ subjective well-being can be affected by dual job demands, as well as their underlying mechanisms and boundary conditions. A structural equation model (SEM) is applied to investigate the mediating role of effort-reward imbalance and the moderating role of overcommitment, and finds that the effort-reward imbalance mediates challenge/ hindrance job demands and subjective well-being, with challenge job demands increasing teachers’ subjective well-being by lowering their effort-reward imbalance, and hindrance job demands decreasing their subjective well-being by increasing their effort-reward imbalance. Moreover, overcommitment positively moderates the effect of the effort-reward imbalance on teachers’ subjective well-being and the effect of hindrance job demands on teachers’ subjective well-being. Overcommitment negatively moderates the effect of challenge job demands on teachers’ subjective well-being. This study uncovers the underlying mechanisms and boundary conditions of the impact of dual job demands on teachers’ subjective well-being, enriched the theoretical use of Job Demands-Resources Model in the field of teaching, and based on which we can put forward effective suggestions regarding the enhancement of the well-being of primary and secondary school teachers.</p>