In this study,the cucumber seedlings were infected by Pseudoperonospora cubensis,and the gene of hypersensitive induced reaction proteins (CsHIR1) was cloned.The prokaryotic expression vector of pET28a-CsHIR1 was constructed and efficiently expressed in E.coli BL21(DE3).The induced expression duration and the concentration of IPTG were optimized.The recombinant protein was purified by cobalt chelating chromatography to prepare the high titer polyclonal antiserum.The results showed that CsHIR1 were expressed in the form of inclusion body,and the optimal induction duration and IPTG concentration were 4 h and 0.5 mmol·L^-1,respectively.High purity recombinant protein CsHIR1 with molecular weight 34 kD was obtained.Western blotting results showed that the antibody of CsHIR1 has good specificity.The prokaryotic expression system establishment and polyclonal antibodies preparation lay the foundation for further investigating the function of the CsHIR1 gene in cucumber.