Objective To investigate the morphology and the root canal system of the maxillary first premolars, and to provide reference for the endodontic treatment. Methods Vernier was used to measure the length indexes. Macrography was used to observe the morphology of the root. X- ray technique was used to investigate the root canal systems. Results All indexes′measurements assumed a normal distribution, in which root length and tooth length were more variable. Correlation and linear regression were significant about the crown length- tooth length and root length- tooth length and also generally existed among other indexes. 74.3% of 105 maxillary first premolars had fused or conical roots. Most teeth had two canals（68.5%）, in which the main types were typeⅠ, typeⅡ, type Ⅳ and type Ⅴ. Conclusion The method may be applied for the root canal treatment of the maxillary first premolars in Chengdu, and the teeth have a high ratio of more than one root canal（71.4%）, which should be paid attention to.
