Objective: Based on the perspective of positive psychology, a moderated mediation model was constructed to examine whether hopelessness mediated negative life events and college students’ suicidal ideation, and whether this mediating process was moderated by meaning in life. Methods: A sample of 842 college students was surveyed to explore mediating and moderating effects. Results: (1) Negative life events had a significant prediction on college students’ suicidal ideation (β =0.33, t=10.30, p<0.001), and the prediction still significant with the intermediary variable added into the model (β =0.26, t=8.04, p<0.001); (2) Negative life events significantly predicted hopelessness (β =0.26, t=7.95, p<0.001), hopelessness significantly predicted college students’ suicidal ideation (β =0.29, t=8.68, p<0.001); (3) Added meaning in life into the model, the products of hopelessness and meaning in life had a significant prediction on college students’ suicidal ideation (β =-0.07, t=-2.36, p<0.05). Conclusion: Negative life events significantly positively contributed to suicidal ideation. Hopelessness played a mediating role between negative life events and suicidal ideation. The mediating effect of hopelessness on college students’ suicidal ideation was moderated by meaning in life. The negative effect of hopelessness on suicidal ideation diminished as the sense of meaning in life increased.