In order to explore the role of MNSFbeta in the process of implantaion, MNSFbeta and its antibodies are required. The expression plasmid pBV220/MNSFbeta-hCGbeta was constructed, and then transferred into E. coli to express the fusion protein MNSFbeta-hCGbeta. The anti-hCGbeta antibody was used to identify the fusion protein. The result demonstrated that MNSFbeta-hCGbeta was expressed correctly and its molecular weight was consistent with the anticipated one. Finally the expression product MNSFbeta-hCGbeta was preliminarily purified and used to immunize Balb/C mouse to generate the antibodies. In the meantime, the expression plasmid pGEX-4T-2/MNSFbeta was also constructed and transferred into E. coli to express the fusion protein GST-MNSFbeta. GST-MNSFbeta was purified and used to stimulate the immunized mouse before the preparation of hybridomas cells. The prepared polyclonal and monoclonal antibodies against MNSFbeta were checked and measured by fusion protein GST-MNSFbeta. The prepared polyclonal antibody was then used to perform the immunohistochemistry analysis. The result suggested that the level of MNSFbeta in interimplantation sites was significantly higher as compared with implantation sites in the mouse uterine on Day 4.5 of pregnancy.