PCR technique is used to amplify the mature peptide gene of human transforming growth factor pl (hTGFbeta1); the gene is verified by full-length sequence analysis. In DHSalpha/pBV220 expression system, hTGFbeta1 attains expression in the cytoplasm of E. coli up to 16%. The recombinant protein is proved to be the monomer of hTGFbetal by N-terminal amino acids analysis and immunoblotting. After refolding of the monomer protein in vitro in glutathione system or CHPAS/DMSO system, the dimeric protein accumulates to 30% in the refolding mixture. The recombinant protein is purified to homogeneity on silver staining, and is shown to have strong biological activity from MTT bioassay on MvlLu cells.