In this study, we cloned a partial cDNA sequence of Dsx (MroDsx) containing DM domain in the fresh water prawn Macrobrachium rosenbergii. The DM domain includes five conserved cysteines and two histidine, and shares 73% similarity with those of Dsx gene of the Chinese shrimp Fenneropenaeus chinensis. Quantitative PCR (qPCR) showed that MroDsx was specifically expressed in gonads, and the expression level in testis was significantly higher than that in ovary. The expression of MroDsx is particularly high in the early testis, and gradually decreased with the development of testis. In situ hybridization (ISH) results further showed MroDsx transcript is highly expressed in spermatogonium, weak in the spermatocyte and spermatid, and not expressed in spermatozoa, which is highly consistent with the results of qPCR. Based on the expression analysis of MroDsx transcript, it is implied that MroDsx may be involved in the testis development of Macrobrachium rosenbergii.