In order to improve the purity of infectious bursal disease virus(IBDV) VP2 protein,this study expressed VP2 protein in Escherichia coli,optimized purification methods and estimated its immunogenicity.VP2 protein was identified by SDS-PAGE and Western blot.The titer of VP2 protein was evaluated by the agar gel immunodiffusion test(AGP). To determine the optimal purification conditions,the target protein was purified by saturated ammonium sulfate solution and ion exchange chromatography,and various steps in proteins purification were optimized to determine the optimal purification conditions including the purified packing,eluent concentration and pH value of the buffer.Then,SPF chickens were immunized with the purified VP2 protein,and the immunogenicity of VP2 protein was determined with ELISA by detecting the periodically collected blood.The results showed that VP2 protein was 50 ku and had good reactogenicity by SDS-PAGE and Western blot,and the titer of VP2 protein determined by AGP was 1∶16.Using a strong anion column to optimize the salt ion concentration and pH value,a higher purity VP2 protein could be obtained with concentration of 0.6 mg/mL.Twenty-eight days after immunized with purified VP2 protein and commercial adjuvant,the titer of specific antibodies was the highest,and the protection rate could reach 80%.No obvious histopathological damage was found in the bursal.Above all,VP2 protein was successfully expressed in Escherichia coli,and the purification method was optimized.The purified VP2 protein had high purity and good immunogenicity.