A new subunit vaccine against infectious bursal disease (IBD) was developed; the antigen used in the vaccine was expressed by a new engineering strain, E. coli BL21/pBV220-VP2. The study on the production and use of the vaccine was performed. The results showed that the recombinant VP2 was water-soluble and demonstrated natural antigen activity in vitro. The antibody induced by rVP2 subunit vaccine could protect chickens from challenges of IBDV strains, both BC 6/85 and JZ 3/02. The vaccine, in which the VP2 AGP titre is 1:4, would be enough to protect SPF chickens of 19-day-old, but seemed to be relatively lower to protect commercial Avian Broilers under 10-day-age. In field study, Avian Broilers were vaccinated with rVP2 subunit vaccine of 1:16 AGP titre at the age of 7 days. The protection rate was varied from 72% to 95% in different chicken farms. To study the method of serological evaluation, antibody respond to vaccination had been detected with three kinds of tests. The correct ratio of detection decreased in the order of VP2-based ELISA, AGP test, and virions-based ELISA, if the result of IBDV detection was used as standard of judging. Correlation coefficient between the OD values of VP2-based ELISA and the virions-based ELISA was 0.782. The results will make it possible for the vaccine to be produced commercially and used in poultry industry in large scale.