Chorionic gonadotropin (CG) is a placental derived hormone that plays a crucial role in successful implantation and establishment of early pregnancy in the primates. The rhesus monkey was chosen as a model to understand the feasibility of developing human DNA immuno-contraceptive. The coding region of rhesus monkey CG β-subunit (rmCGβ) was isolated by the TDRT-PCR method. The nucleotide sequence including the leader peptide was 499 nucleotide long and encoded 166 amino acids. In comparing with the previous known primates CG β-subunits, the rmCGβ was the highest degree of homology with baboon CG β-subunit at the deduced amino acid sequence (94%), 79.5% homology with human CG β-subunit and 70.4% homology with marmoset monkey CG β-subunit. The eukaryotic expression vector pCMV4-rmCGβ inserted full-coding cDNA sequence of rmCGβ was constructed, and the expression of rmCG β-subunit in HeLa cells transient expressing system in vitro and BALB/c mice in vivo was determined. The results demonstrated that the recombinant PCMV4-rmCGβ eukaryotic expression vector could express rmCG β-subunit in vitro and in vivo.