〔Abstract〕 ThePSCAgene encoding prostate stem cell antigen(PSCA) andPaFvgene encoding PSCA-specific scFv antibody were amplified and cloned into pET-32 a and pDAP2/S vectors, respectively. After induced for expression of TrxA-PSCA and PaFv-AP fusion proteins, SDS-PAGE and Western blot were conducted to analyze their expression levels and forms, whereas alkaline phosphatase(AP) color-reaction and enzyme-linked immunosorbent assay(ELISA) were applied to detect the activity of PaFv-AP fusion. The results suggested that TrxA-PSCA and PaFv-AP fusion proteins were successfully expressed in soluble form in the constructed prokaryotic expression systems. Moreover, the PaFv-AP fusion retained the antigen-binding capacity of antibody and AP activity.