Objective To investigate the effects of sleep quality and depressive symptoms on the relationship between internet addiction and suicidal ideation in adolescents, and to provide evidence for targeted intervention.Methods A total of 509 middle school and high school students were selected from two schools using convenience sampling method and invited to complete a battery of questionnaires,including a general information questionnaire, the Revised Chen Internet Addiction Scale (CIAS-R), Columbia Suicide Scale Brief Screening Version (CSSBSV), the Pittsburgh Sleep Quality Index, and the Center for Epidemiological Studies Depression Scale.A chain mediation model was constructed.Results Among 509 participants, 25.74% had a certain tendency of internet addiction, 11.79% had poor sleep quality, 27.90% had depressive symptoms, and 45.97% had suicidal ideation in the past year.Internet addiction directly affected suicidal ideation (direct effect accounted for 60.20% of the total effect).There was a chain mediating effect of sleep quality and depressive symptoms on the relationship between internet addiction and suicidal ideation (indirect effect accounted for 7.65% of the total effect).Conclusion Some adolescents have internet addiction, poor sleep quality, depressive symptoms and suicidal ideation.Internet addiction not only directly affects suicidal ideation, but also indirectly affects suicidal ideation through sleep quality and depressive symptoms.Schools and parents should adopt targeted strategies to protect adolescents′ physical and mental health.