Human IL-6,IL-10,IL-13 and SCF cDNAs encoding extra - cellular domain were isolated by reverse transcription polymerase reaction (RT-PCR). These cDNA fragments were inserted into expression vector PBV220 which contains PRP_(L), promoters and SD sequence. Then the E. coli DH5? were tronsformed with the recombinant plasmids. After screening, the clones carrying those recombinant plasmids were identified. SDS-PAEG and biological assay indicated that human IL-6, IL-10 and IL-13 were expressed in E.coli. The expression level of rhIL-6 was as high as 30% of the total bacterial protein.