Abstract: To analyze the expression pattern of Doublesex(dsx)of Daphnia pulex in different reproductive modes,we extracted total RNA of different reproductive modes’Daphnia pulex.Using RT-PCR and Quantitative real-time PCR analyzed dsx expression in different reproductive modes’ daphnias.In addition,we synthesized DIG labeled RNA probe of dsx by in vitro transcription and used whole mount in situ hybridization researching dsx location expression in different reproductive modes’ daphnia.Results showed that dsx in male and female had no gender specificity of alternative splicing,only a same transcription.Real-time PCR showed dsx highest expression level was in male,which was parthenogenetic female’s 2.6 times and 4.9 times that of the female.They had significant difference(P <0.05)and gender differences in expression each other.Whole mountin situ hybridization found that dsx gene was expressed in the somatic tissure in different from reproductive modes’ daphnia,but the difference in quantity and parts.The expression also showed the gender differences in male and female.In male the signals were revealed in the first antenna,the first thoracic limb and the compound eye.The parthenogenetic female and sexual female corresponding sites’ expressions were relatively weak.These suggested that Doublesex gene likely played a significant role in alternation of generation and sexual differentiation.