DMRT1, an important member of the DMRT family, is mainly involved in sex determination and sex differentiation regulation in animals, but its expression characteristics and function are different in different species. In the present study, we analyzed Chlamys farreri Dmrt1 sequence characteristics using bioinformatics methods; determined Dmrt1 mRNA tissue distribution in adult gonad, adductor muscle, mantle, gill, and kidney tissue using semi-quantitative RT-PCR; and revealed its spatiotemporal expression pattern in C. farreri gonads using quantitative RT-PCR and in situ hybridization. The results showed that the deduced amino acid sequence of DMRT1 contained the conserved DM domain of the DMRT family; its mRNA was expressed exclusively in the gonads, and the mRNA levels in the testes were significantly higher than those in the ovaries, and it was the highest in the testis at the growing stage. Moreover, Dmrt1 positive signals were located in C. farreri germ cell cytoplasm. We suggested that Dmrt1 expression characteristics in C. farreri adult gonads is consistent with that in most animals, and may be involved in regulating C. farreri sex differentiation and testis development.