T lymphocytes are the major components of adaptive immunity in Behçet's syndrome (BS) pathology. However, the precise mechanism of T‐cell‐induced inflammatory condition remains to be determined. We applied bulk sequencing of the T‐cell receptor (TCR) β chain in peripheral blood samples from 45 patients with BS and 10 healthy donors as controls. TCR repertoires in BS patients displayed more clonality and less diversity than in healthy donors. Male patients exhibited lower diversity metrics of TCR and had a larger proportion in the top 10 clones than females (p = 0.016). There were no TCR clonality differences in other clinical features, such as age, disease duration, organ involvement, disease severity, and activity. By “Grouping of Lymphocyte Interactions by Paratope Hotspots” (GLIPH2) for antigen prediction, we found distinct 2477 clusters of TCR‐β sequences that potentially recognize similar antigens shared between BS patients. We observed clonal T‐cell expansion in BS patients. Sexual differences in TCR clonal expansion and public TCR groups deserve further study to reveal the underline T‐cell‐mediated immunity in BS. Bulk sequencing of the TCR repertoires in BS patients displayed more clonality and less diversity than in healthy donors. Male patients exhibited lower diversity metrics of TCR than females. GLIPH2 predicted distinct clusters of TCR‐β sequences in BS patients.