Objective To analyze the pathways and mechanisms underlying the impact of guilt on suicide risk using a well-controlled longitudinal study, we examined the mediating roles of intrusive rumination, deliberate rumination, and posttraumatic stress disorder (PTSD) in this association. Method Four hundred and eight adolescent survivors (Mage = 14.05 years) were assessed using self-report questionnaires three and a half years and four and a half years after the Ya'an earthquake. The self-report questionnaires included the Trauma Exposures Questionnaire, the Interpersonal Guilt Questionnaire, the Event-Related Rumination Inventory, the PTSD Checklist for the DSM-5, and the Child Behavior Problems Questionnaire. Results The results indicated that guilt had a direct and positive effect on suicide risk. Intrusive rumination and PTSD mediated the relationship between guilt and suicide risk. Guilt could increase deliberate rumination, but deliberate rumination did not significantly predict PTSD and suicide risk. Conclusion Negative postdisaster emotions, such as guilt, can enhance the combined effects of cognition and psychological disorders on suicide risk. Guilt affects suicide risk indirectly through intrusive rumination and PTSD but not through deliberate rumination.