To elucidate the function of the doublesex（PcDsx）gene in Procambarus clarkii ,the PcDsx cDNA sequence was obtained by the rapid amplification of cDNA ends (RACE) and the expression of PcDsx was determined by quantitative realtime PCR (qRT-PCR). The results of bioinformatics analysis showed that the fulllength PcDsx cDNA was 1 584 bp,with a 243 bp 5′ untranslated region,a 765 bp open reading frame (ORF) (coded 254 aa) and a 576 bp 3′ untranslated region. The deduced protein of PcDsx was 254 aa and the predicted PcDsx protein was found to contain a conserved DM domain. Phylogenetic analysis revealed that the PcDsx DM domain share high similarity to the DM domain of Sagmariasus verreauxi doublesex. The gene expression analysis showed that PcDsx was widely expressed in various tissues of the adult crayfish,highest in the antennary glands,followed by the muscle and gonads. The expression of PcDsx in various adult female tissues was significantly different from that in adult male tissues. During the early development of P. clarkii ,the expression level of PcDsx reached a peak at 3 day after hatching,while the highest expression of PcDsx in male and female juveniles appeared at 41 and 115 day after hatching,respectively. Besides,the expression of PcDsx also showed significant differences between male and female juveniles.