Abstract: Objective: To investigate the canal morphology of bilateral mandibular first premolars in Uighur population of Xinjiang using cone-beam computed tomography (CBCT). Methods: A total of 200 CBCT images of mandibular first premolars were obtained from 100 patients. Tooth position, root canal morphology, symmetry of bilateral mandibular first premolars, and the distance between the 2 root canal orifices of mandibular first premolars were investigated. The classifications of the root canal types were according to Vertucci's type. Results: 1.5% (n=3) of the teeth had a C-shaped root canal system, 76.5% (n=153) had 1 root canal, and 22% (n=44) had 2 root canals from type II to type V. The distance between the 2 root canal orifices of mandibular first premolars was approximately 1-3 mm, and the symmetry in all types of canal classification of mandibular first premolar was 85%. Conclusion: CBCT can provide accurate information of canal system. More than 20% of mandibular first premolars had complex root canal systems showing multi-canal or double root canals.