Tsunagi is an evolutionally conserved RNA-binding protein that is required for the maintenance of oogenesis and masculinization of the germ line in many animal models．We speculated that Tsunagi may also regulate reproductive organ development in Schistosoma japonicum．We introduced S．japonicum Tsunagi double-stranded RNA into schistosomula by electroporation．These transfected schistosomula were cultured in vitro，and the mRNA and protein levels of the target gene were found to be significantly suppressed by interference．Further，BALB／c mice were infected witll the transfected SChistosomula for 6 weeks and sacrificed for harvesting adult worins．We found that silencing of S．japonicum Tsunagi led to defects in the development of reproductive organs in both male and female worms．Moreover，it affected the production and development of eggs．Our study indicates that Tsunagi plays a critical role in the development of reproductive organs and eggs in Schistosoma japonicum．