Abstract:  Coding DNA sequences (CDS) of 208 proteins in Astacidea were analyzed in the present study. The content of G+C at three positions of codons， ENC (effective number of codon) of genes and frequency of synonym codon usage were calculated by the software CodonW 14， and the “optimal codons” were also determined. The results showed that the content of G+C at the third position of codons was significantly higher than that of the first and second positions， and genes preferred to the codons with C or G at the synonymous position. In addition， 9 codons were determined as the “optimal codons”， which were ended with G or C. The data would offer references in the research on new gene search， gene expression， forecast of protein function and structure， and comparative genome with other shrimps.

Key words: Astacidea, codon bias, optimal codon