Objective To analyze the monitoring data of adverse event following immunization (AEFI) in Bengshan District of Bengbu City,and to understand the occurrence and epidemic characteristics of AEFI,so as to provide reference basis for vaccination safety research and the current COVID-19 vaccination work. Methods AEFI case information and vaccination information from 2012 to 2020 in Bengshan District were collected through AEFI Information Management System and Anhui Immunization Planning Information System,and analyzed by descriptive epidemiological method. Results A total of 268 cases of AEFI were reported in the region from 2012 to 2020,with a reported incidence of 39.64/100,000 doses,of which the highest in 2020 (76.64/100,000 doses) and the lowest in 2017 (21.37/100,000 doses).The difference in the reported incidence was statistically significant (χ²=47.891,P＜0.001).AEFI reports mostly in the second and third quarters,accounting for 70.52% of the entire year.The incidence of general reaction and abnormal reaction were 35.21/100,000 and 4.14/100,000 doses,respectively.The incidence of coupling disease was 0.30/100,000 doses.There were no psychogenic reactions,no reports of vaccination accidents and vaccine quality accidents.The incidence of severe AEFI was 0.44/100000 doses.The ratio of male to female was 1.68:1,with the highest proportion of children≤1 year old,accounting for 69.78%.The number of reported cases in the top three were Acellular DPT vaccine,Diphtheria-Tetanus vaccine,hepatitis B vaccine,and a total of 178 cases were reported,accounting for 66.42% (178/268). Conclusion The AEFI monitoring system in Bengshan District operates well,the AEFI monitoring system has high sensitivity and good vaccination safety.