A high level expression vector pRC has been constructed, which contains P_R promoter, cIts857 gene, multiple cloning sites(MCS) and two strong transcription terminators. With this vector, hTNF-α, hIL-3 and anti-HEL McAb Fd genes have been expressed successfully, and their products each account for more than 36% of the total cell proteins. At the same time, it has been studied whether such factors as procaryon enhancer sequence and different strains affect the expression level of P_R promoter vector. Furthermore, the inductive efficiency was compared among P_R, P_L and P_RP_L promoter, and the result has showed that P_R or P_L is as strong as P_RP_L.