Objective: To explore the prevalence and co-morbidity in depression disorder among children and adolescents in Chengdu City. Methods: Using a one-phase design, 4S8S children and adolescents in grades 1～10 were assessed with the Strength and Difficulty questionnaire (SDQ) and Development and Well-Being Assessment (DAWBA) . A structured interview with verbatim reports was reviewed by clinicians so that information from parents, teachers, and children were combined in a manner that emulated the clinical process. Results: (1) The rate of depressive disorder was 1.2% , and that in girls was much higher than that in boys after 12 years old (2.56% vs. 1.42%) . (2) The rate of depressive disorder increased with age from 0.10% (6～8 years) to 2.59% (≥ 15 years) . (3) The co-morbidity was 40% . The most common comorbidity diagnosis was anxiety disorders (29.1%) and behavior disorders (25.5%) . Conclusion: The prevalence of depressive disorder among children and adolescents in Chengdu is 1.2%. Gender and age may be the related factors. The co-morbidity is common in children and adolescents with depression disorder.