Abstract: Objective: To explore the differences of obsessive beliefs and anxiety traits between patients with obsessive-compulsive disorder (OCD) and their relatives at different onset ages and their correlation with therapeutic effects. Methods: Obsessive Beliefs Questionnaire-44 (OBQ-44) and State Trait Anxiety Inventory (STAI) were used to assess patients and relatives with OCD onset in adolescence and adulthood. Yale-brown ObsessiveCompulsive Scale (Y-BOCS) was used to assess obsessive-compulsive symptoms in patients. Results: Compared with adult-onset obsessive-compulsive disorder patients, adolescent-onset patients had higher total scores on the OBQ-44 and the STAI (t=2.090, P=0.043; t=2.327, P=0.025), the relatives of the two groups also showed a similar trend (t=2.901, P=0.006; t=3.357, P=0.002). The total scores of obsessive beliefs and anxiety states/traits of the relatives of patients were positively correlated with the obsessive thoughts of patients before treatment (r=0.393, P=0.012, r=0.557, P＜0.001). The obsessive beliefs and anxiety states/traits were also positively correlated with the compulsive behaviors of patients before treatment (r=0.320, P=0.044, r=0.662, P＜0.001). The anxiety traits of the relatives of patients were negatively correlated with the reduction of obsessive-compulsive symptoms (r=-0.389, P=0.013). Conclusion: Adolescence-onset patients with OCD and relatives have more pronounced obsessive beliefs and anxiety states/traits, and the cognitive characteristics of relatives are associated with disease severity and prognosis. Therefore, it is necessary to pay attention to the evaluation of cognitive characteristics of patients and relatives in OCD, especially in patients with early onset.