Objective To analyze the surveillance quality and characteristics of adverse events following immunization(AEFIs)in Shaanxi Province,from 2010 to 2021.Methods The vaccine doses administered data and AEFI data reported from 2010 to 2021 in Shaanxi Province were collected through the National Immunization Program Information Management System and AEFI information management system,and descriptive epidemiological methods were used for analysis.Results A total of 24 057 AEFIs were reported from 2010 to 2021 in Shaanxi Province.The average annual reported incidence of AEFI in 2014-2021 was 18.998 per 100 000 doses,with 17.998,0.702,and 0.112 per 100 000 doses for common vaccine reactions,rare vaccine reactions,and serious rare vaccine reactions,respectively.The incidence of AEFI was high from May to August,with an average of 26.304 per 100 000 doses.There were 69.83% of the cases reported by the children younger than 1 year old.In Expanded Program on Immunization vaccines,the incidence of AEFI in DTaP(diphtheria,tetanus and acellular pertussis combined vaccine)was the highest(57.948 per 100 000 doses),and the incidence of rare vaccine reactions in MR,MMR and MM(measles and rubella vaccine,measles mumps and rubella vaccine,measles and mumps combined vaccine)was the highest(1.875 per 100 000 doses).In non-Expanded Program on Immunization vaccines,the incidence of AEFI in DTaP-Hib(diphtheria,tetanus and acellular pertussis,inactivated poliomyelitis and haemophilus influenzae type b conjugate combined vaccine)was the highest(37.073 per 100 000 doses),and the incidence of rare vaccine reactions in MPV-ACYW135(group A,C,Y and W123 meningococcal polysaccharide vaccine)was the highest(2.392 per 100 000 doses).In common vaccine reactions,the fever/local redness and swelling/local induration were the main clinical diagnosis(22.481 per 100 000 doses).In rare vaccine reactions,allergic rash was the main clinical diagnosis(0.473 per 100 000 doses).Conclusion The sensitivity of AEFI surveillance system in Shaanxi Province is increasing year by year,and the vaccines have good safety,with common vaccine reactions as the main ones and serious rare vaccine reactions as the rare ones.There were differences in AEFI surveillance levels in different prefecture-level cities,so it is still necessary to strengthen the training.