The vaccinia viral vector containing T7 promoter was used to construct the expression plasmids carrying HCV structural genes of C, El and E2/NS1. These genes were transiently expressed in mammalian cells in the presence of the T7 RNA polymerase which was provided by the recombinant vaccinia virus vTT7. Expression of mature core protein, envelope protein El and E2 was detected by Western blot using HCV patient sera as the primary antibodies. It was found that the sera from different HCV patients reacted differently with the expressed products, so did the sera collected at different times from the same patient, from whom the HCV structural genes were isolated. Among six mammalian cell lines, Vero and HeLa were the most suitable for the expression of C, El and E2-The recombinant vaccinia viruses have been constructed to constantly produce the C, El and E2 proteins for further research.