Abstract: Objective To understand the incidence patterns of adverse events following immunization (AEFI) in Changping district of Beijing and evaluate the performance of AEFI information management system and the safety of immunization.Methods AEFI surveillance data of Changping from 2008 to 2015 were collected from national AEFI information management system for a descriptive epidemiological analysis.Results During the study period,926 AEFI cases were reported in 20 communities (villages) of Changping.Among them,874 were reported within 24 hours,and 896 were within 48 hours,accounting for 94.38% and 96.76% of the total respectively.Also,920(99.35%) AEFI cases were investigated within 48 hours.The male to female ratio of AEFI cases was 1.25:1;In age distribution,349 cases (37.69%) were aged 1 year,435 cases (46.98%) were aged 1-6 years,and 142 cases (15.33%) were aged 6 years.In term of onset time,826 cases (89.19%) occurred within 1 day after vaccination.From 2008 to 2015,the overall incidence of AEFI was 11.56 per 100 000 in Changping,while the rare reaction incidence was estimated to be 4.07 per 100 000.For all the AEFI cases,fever and local swelling were the common manifestations.Anaphylactic rash and urticaria were the most common abnormal reactions and the serious abnormal reaction was rare.Most AEFI occurred after vaccination.Conclusion In Changping,AEFI occurred mainly in children aged 1 year and usually within the first day after vaccination.The rate of abnormal reaction was within the expected range.The sensitivity of AEFI surveillance has been improved greatly in Changping,but some indexes have not met the requirements of the Vaccination Specification of Beijing,suggesting that the related training and supervision should be strengthened to improve the quality of AEFI surveillance.