nucleotides of the coding region have been sequenced in the mitochondrial cytochrome b gene from Mandarin fish S. chuatsi and the corresponding amino acid sequence has also been deduced. The contents of A+T and G+C are 53.4% and 46.6% respectively。While the first positions of the codons have more or less even usage in 4 nucleotides, the second positions of the codons in the gene have bias to higher T and lower G;and only 3.7% G were found in the third positions. In deduced amino acid sequences, the percentage of Leu used in cytb gene were over twice than any other amino acids, the usage of Cys accounted for only 0.79%. Further studies will determine whether the nucleotide usage in different positions of codons and composition of amino acids were characteristic of S. chuatsi or sinipercinae, and molecular phylogeny and phylogeography of Sinipercinid fishes.