Abstract: In order to determine the species composition of genus Sillago, this study measured 411 Sillago individuals, which were collected from the coastal waters of Zhoushan and Wenzhou, Zhejiang Province. The mitochondrial cytochrome c oxidase subunit 1 (CO I) gene sequences were used for genetic diversity and molecular phylogenetic analysis. The results showed that only Sillago japonica and Sillago sinica distributed in the coastal waters of Zhejiang. These two species were different in morphology, especially in the shape of swim bladder. We obtained 600 bp CO I sequences, and the GC contents for S. japonica and S. sinica in all position were 46.6% and 49.9%, respectively. The mean genetic distances by Kimura-2-parameter model within S. japonica and S. sinica were 0.002 and 0.000, respectively; and the mean genetic distance between S. japonica and S. sinica was 0.211. The NJ tree revealed that all 7 Sillago species formed monophyletic groups. This study classified the Sillago species in the coastal waters of Zhejiang, and reinforced the validity of DNA barcoding on classification of Sillago species based on CO Ⅰ gene.