The importance and dynamic development of technological pedagogical content knowledge (TPACK) has been well recognized. In order to keep up with the development of the ever-changing society and variety of teaching technologies, teachers need to continue to learn TPACK. Previous studies indicated the importance of student engagement in promoting teachers' learning. However, how student engagement affects teachers' continuous learning of TPACK remains unclear. To bridge the research gap, our study constructed a model based on the stimulus-organism-response (SOR) framework and integrative model of behavior prediction (IMBP). It examined how student engagement affects teachers' psychological state and behavioral performance for continuous learning of TPACK. The model was then validated by structural equation modeling with 395 questionnaire data. The results demonstrated the positive relationships between student engagement (behavioral, emotional, and cognitive engagement), teachers' psychological states (attitude, subjective norm, self-efficacy, and behavioral intention), and continuous learning of TPACK. These findings inform how to promote teachers to keep learning TPACK.