Objective:To amplifiy of Trop-2 gene from clinic tumor tissue and express Trop-2 protein in E.coli. TOP10,and analyze its immunological characters with Western blot and ELISA. Methods:The Trop-2 gene was amplifiied by RT-PCR and cloned into pMD18-T. After sequenced,the Trop-2 gene was digested with NcoI and EcoRI and cloned into expression vector pBAD-gⅢ. The constructed vector had been identified by nucleotide sequence analysis,and then transformed into E.coli. TOP10. After induced with L-arabinase,the recombinant protein was purified with HisTrap affinity chromatography,and confirmed by Western blot and ELISA. Results:The Trop-2 was amplicated and sequenced,and the recombinant plasmid was constructed correctly. SDS-PAGE analysis showed that the recombinant protein was about 38 ku. The purified protein could be used as an antigen to detect the specific antibodies with Western blot and ELISA. Conclusion:The recombinant extracellular protein of Trop-2 could be expressed with high performance,and the antigenicity of the purified protein was certificated with the specific antibody.