Objective: To explore the association between negative life events and college student adjustment and to explore the mediating and moderating effects of social support and grade level in the relationship between the two. Methods. The research was conducted with 1717 college students using the Adolescent Self-Rating Life Events Checklist (ASLEC), China College Student Adjustment Scale (CCSAS), and the Social Support Rating Scale (SSRS). Results. (1) Negative life events were significantly negative in correlation with adjustment and social support (r = −0.373, −0.174, Ps < 0.001), while social support was significantly positive in correlation with adjustment (r = 0.359, P < 0.001). (2) The main effects of negative life events, social support, and grade on adjustment were significant (effect = −0.190, P < 0.001, 95% CI [−0.288∼−0.092]; effect = 0.307, P < 0.001, 95% CI [0.265∼0.348]; effect = 0.163, P < 0.001, 95% CI [0.126∼0.200]). (3) In the relationship between negative life events and adjustment, social support played a mediating role (effect = −0.054, 95% CI [−0.071∼−0.037]) and grade level played a moderating role (effect = −0.049, P=0.009, 95% CI [−0.085∼−0.012]). Conclusion. Negative life events, social support, and grade level affected college student adjustment, and social support networks for college students should be actively constructed and targeted education should be conducted according to different grade levels, which can promote college student adjustment.