Objective: To investigate the distribution and clinical significance of antiphospholipid antibody (aPL) in patients with Behcet disease (BD). Methods: A total of 222 BD patients admitted to the Department of Rheumatology and Immunology in Peking University People' s Hospital from February 2008 to July 2024 were selected retrospectively. General data of the patients including age and gender were collec-ted. Clinical manifestations (including oral ulcers, genital ulcers, and thrombosis) and laboratory indexes (including aPL, human leukocyte antigen-B51, and anti-endothelial cell antibody) were collec-ted. The recurrence of thrombosis in the BD patients with thrombosis was followed up. Chi-square test was used to compare the clinical symptoms and laboratory indicators between aPL positive group and aPL negative group. Log-rank test was used to compare the recurrence rates of the aPL positive group and the aPL negative group, and P correction was performed by Two-stage method. Finally, Graphpad prism was used for plotting. Results: The prevalence of single aPL, double aPL and triple aPL positivity in the BD patients were 22.1%, 0.5% and 1.4%, respectively. The positive rates of anti-cardiolipin antibody, anti-β2 glycoprotein Ⅰ antibody and lupus anticoagulant (LAC) were 10.4%, 1.8% and 13.1%, respectively. The incidence of thrombosis in the aPL positive group was significantly higher than that in the aPL negative group (44.9% vs. 16.9%, P < 0.001). The erythrocyte sedimentation rate [(20.78±4.91) mm/h vs. (15.85±4.29) mm/h, P=0.005], C-reactive protein [(12.97±5.17) mg/L vs. (7.49± 4.22) mg/L, P=0.010] and IgM [(1.55±0.95) g/L vs. (1.12±0.72) g/L, P < 0.001] in the aPL positive group were significantly higher than those in the aPL negative group. LAC positivity was an independent risk factor for thrombosis in the BD patients (OR=8.51, 95%CI: 2.71-26.72, P < 0.001). The recurrence rate of the aPL positive group was higher than that of the aPL negative group, but there was no statistical difference (69.23% vs. 52.17%, P=0.932). Conclusion: Positive LAC and aneurysm are independent risk factors for thrombosis in BD patients. At the same time, positive antiphospholipid antibody can also significantly increase the risk of thrombosis in BD patients, which has important significance for guiding the treatment of BD.