In this paper,Trionyx sinensis was used as research material,the difference of mitochondrial cytochrome b gene(Cytb) was compared and analyzed between Trionyx sinensis and Palea steindachneri or Pelodiscus axenaria. Cytb gene from HanShou Trionyx sinensis was cloned by using the PCR technology,and the expression patterns of different tissues and different growth stages were detected. Finally,the genetic relationship between Trionyx sinensis and Pelodiscus axenaria was used to analyze through molecular phylo...