The purpose of this study was to examine the correlation between perceived teacher autonomy support (PAS) and student engagement (SE), as well as the mediating role of learning motivation (LM) and the moderating role of the class climate (CC) among 1517 college students in Chinese universities. Survey questionnaires were used in gathering data, and the findings revealed that: (1) PAS had a significant positive impact on SE (B=0.966, p<0.001); (2) LM partially mediated the association between PAS and SE (B=0.084, p<0.001); (3) CC moderated the relation between PAS and LM (B=1.895, p<0.001); more specifically, favorable CC strengthened the effect of PAS on LM among college students. From the findings, this study contributes to a better comprehension of the influence of PAS on SE among Chinese college students. It is suggested higher education institutions and teachers should pay attention to college students' PAS, LM, and CC to improve college students' engagement.