To gain a better understanding of the role in gonadal development of StAR in Pelodiscus sinensis, we cloned StAR cDNA full length of 2 377 bp, containing an open reading frame (ORF) for 300 amino acid residues. The predicted StAR of P. sinensis was maximally identical with turtle StAR protein. qRT -PCR result revealed that StAR mRNA was checked in seven different tissues of the turtle, among which the maximum level was detected in testis. The StAR mRNA had been expressed at embryonic 16th stage. In the study, the male turtle was treated by letrozole, and the results showed that the level of StAR mRNA expression increased rapidly compared to the control firstly, and then the expression levels decreased. The recombinant plasmid was constructed and the StAR polyclonal antibody was obtained by immunizing mice. Western blot analysis showed that the expression of StAR in different tissues was consistent with qRT-PCR result. Immunohistochemical results showed that StAR protein was expressed in ovarian stromal cells. Therefore, the StAR gene might play an important role in gonadal differentiation, steroid hormone synthesis and spermatogenesis in P. sinensis.