Objective To explore the the epidemiological status,characteristics and the major causes of accidental mortality in children under five years old in Chengdu,China and provide scientific basis for policy setting to reduce the under-5 mortality. Methods A retrospective analysis was conducted through a province-based surveillance networkin in Chengdu from 2005 to 2014.The accidental mortality and the major causes in children under 5 years old were analyzed by trend chi-square test and rank test with SPSS 19.0 software. Results The decline trends of the total mortality in children under 5 years old were found in Chengdu from 2005 to 2014,especially in neonatal and the infant above 28 days.The mortality of children aged 1 to 4 years old and the accidental mortality of all ages did not show the significant decline trends.However,the proportion of accidental death in total mortality increased in children under 5 years old (χ²=4.50,P=0.03).Accidental suffocation was the leading cause of accidental deaths among the newborns and infants,making up 88.37% and 83.85% of the total accidental deaths,respectively.Drowning and traffic accident were the top two causes of accidental death in children aged 1 to 4 years old,making up 58.16% and 16.51%,respectively.The accidental mortality in urban areas did not decline (P＞0.05),while the accidental mortality in rural areas decline (P＜0.05).The causes of death were different between the urban and rural areas.The three leading causes of death in urban areas were accidental asphyxia (38.48%),drowning (22.49%) and traffic accidents (15.44%); Unlike the main causes in urban areas,the three leading cause were drowning (41.45%),accidental asphyxia (33.79%) and traffic accident (12.08%) in rural areas. Conclusions Accidental injury has become the major causes of death in children under 5 years old in Chengdu.Accidental injury should be strengthed to reduce the mortality in children under 5 years old.Enhancing the health education for parents and improving social emergency management system are the important strategies to reduce the accidental mortality in children under 5 years old in Chengdu.