Abstract: In the present study, GHRH gene was cloned into pCMV-Rep-lacZ which digested by BamHⅠin order to replace the LacZ gene with our gene of interest and dephosphorylated by shrimp alkaline phosphatase, creating pCMV-Rep-GHRH. pCMV-Rep-GHRH was transfected by Lipofectin to prepared 293 cells. Results of RT-PCR, Tricine-SDS-PAGE ,Western Blot and immunofluorescence antibody assay(IFA) showed the our interested gene was expressed efficiently in transfected 293 cell. In order to compare the expressed efficacy between RNA replicon vector(pCMV-Rep-GHRH) and ordinary vetor（pIRES-GHRH and pCDNA3-GHRH）, we also detected the concentration of GHRH from transfected cell supernatant by RIA in this study. The results showed that the concentration of GHRH from pCMV-Rep-GHRH transfected cell supernatant was 36.12%（P<0.05）and 67.94%（P<0.05）higher signifiantly than that of GHRH from pIRES-GHRH and pCDNA3-GHRH transfected cell supernatant respectively. We conclude that that GHRH can be expressed efficiently in eukaryotic expression vetor pCMV-Rep-GHRH transfected 293 cell. We can also draw another conclusion that the express level of RNA replicon vector was superior to ordinary vetor. It may be a potential way to increase animal productivity.