Backgrounds Associations between attention deficit hyperactivity disorder (ADHD) subtypes and suicidal behaviors remains unclear. The current study explored the prevalence of suicidal behaviors, and its association with ADHD among Chinese medical students. Methods Five thousand six hundred ninety-three medical college students participated. Symptoms of suicidal behaviors, ADHD, anxiety, depression, tobacco and alcohol use were assessed using online questionnaires. Results The prevalence of lifetime suicidal ideation, suicide plans, and suicide attempts among medical college students were 27.5, 7.9 and 14.8% respectively. Participants with ADHD predominantly inattentive type (ADHD-I) had more than fivefold increased odds of suicidal behaviors, the adjusted odds ratios (ORs) of ADHD-I and ADHD combined type (ADHD-C) remained significant after controlling for confounding factors. Conclusions ADHD is associated with high risk of suicidal behaviors. ADHD-I and ADHD-C were strongly associated with suicidal behaviors independent of comorbidities. The finding suggests the importance of addressing ADHD symptoms in suicide prevention.