To explore the relationship between absolutizing and catastrophizing beliefs and obsessive-compulsive symptoms and to examine the interactions between beliefs. Ninety-nine outpatients and inpatients with obsessive-compulsive disorder (OCD) in Nanjing Brain Hospital were selected for two longitudinal follow-up surveys with an interval of 3 months. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) was used to measure the severity of obsessive-compulsive symptoms; the Absolute Belief Scale and Catastrophic Belief Scale were used to assess the level of beliefs; and the Obsessive-Compulsive Belief Questionnaire (OBQ-44) was used to measure obsessive-compulsive beliefs. Bootstrap results showed that catastrophizing beliefs fully mediated between absolutizing beliefs and obsessive-compulsive symptoms in patients with OCD, with a mediating effect size of 0.02 (95% CI: 0.01~0.03). Cross-lagged regression showed that the pretest absolute beliefs related to others had a significant predictive effect on both self-evaluation (β=0.238, P<0.05) and others' evaluation (β=0.278, P<0.05) factors of catastrophizing beliefs in the posttest. Catastrophizing beliefs of OCD patients may fully mediate between absolutizing beliefs and obsessive-compulsive symptoms; the others-related factor in absolutizing beliefs predicts the belief levels of both self- and others-rated factors in catastrophizing beliefs.