Rad23 gene which participates in ubiquitin/26S proteasome pathway in Arabidopsis， is known to play important roles in plant development and responses to hormone. In order to study its function and molecular mechanism, an expression vector pCold-Rad23 was constructed and transformed into E. coli BL21. Then the recombinant fusion protein was induced by IPTG.The results of SDS-PAGE have shown that Rad23 fusion protein existed in a soluble form with a relative molecular mass 94 ku, which is fit for the molecular mass supposed from gene coding frame. Finally, the Rad23 recombinant fusion protein was used as an antigen to prepare polyclonal antiserum in mice. The western blot results have shown that the polyclonal antiserum has high specificity and can react to the native protein expressed in different tissues of Arabidopsis.