The Sweetfish Plecoglossus is a kind of amphidromous fish endemic to east Asia. In order to determine taxonomic status of controversial Chinese sweetfish, mitochondrial cytochrome b gene sequences of 2 Chinese sweetfish from Liaoning and Guangdong were determined, combined with 9 GenBank-downloaded homologous sequences of the same genus from Japan and South Koea, 11. individual fishes were analyzed. Of the aligned 402bp nucleotide sequences, there existed 8 variable sites and 2 information sites. The contents of A+T and G+C of the gene are 51.4%, 48.6%, respectively. The ratio of transition verse transversional is 4.9. Kimura-2 parameter model based neighbour-joining tree indicated that Chinese sweetfish mosaic clustered with those from Japan and South Korea; no geographic structure within and between geographic populations were found, and genetic distance among different populations were equivalent, suggesting that they were closely related. According to the geographic distribution of abroad populations, they might belong to the same subspecies of P.altivelis altivelis. As Chinese sweetfish were nested within and genetic closely related to others, Liaoning and Guangdong sweetfish might belong to P.altivelis altivelis too. As no sequences from P.altivelis ryukyuensis were available to our study, this conclusion needs further research. Although no obvious genetic structure were found between Liaoning and Guangdong populations, it did not necessarily mean that all Chinese sweetfish belong to the same subspecies, as diversified coastal regions and habitats might exist in China, and sample size were limited and cytb is relatively conservative in this study. To determine the taxonomic status and populations structure of Chinese sweetfish, intensive and extensive population samples are needed using both mitochondrial and nuclear markers.