In order to express ascorbate peroxidase(Apx) gene of Chinese kale in E.coli,we amplified apx coding sequence of Chinese kale by means of PCR and RACE based on the conserved sequence of ascorbate peroxidase gene in Brassica.Analyzed and calculated by DNAMAN V6,the molecular weight of recombinant protein was approximately 27.6 kDa.We constructed recombinant plasmid pET-28a-apx and transformed it into E.coli BL21.The Apx was expressed successfully in E.coli BL21 with the soluble form.The results from single-factor experiment showed that the optimal condition for Apx expression was induction at 23 ℃ for 10 hours with the addition of 0.2 mmol / L IPTG.The recombinant protein was purified by Ni2 +affinity chromatography and the best reaction condition for the enzyme was at pH6.5 and 40 ℃.The results provided the basis for the physiological and functional research of Chinese kale Apx.