Objective To determine the trend of emergency department (ED)mortality of a tertiary general hospital from 2004 to 2014 in order to find the factors that may impact on ED mortality.Methods Mortality in ED was estimated according to the ratio of ED visiting patients to ED deaths.And the data of all ED deaths in 2004,2009 and 2014 were collected.Variance analysis and chi-square test were used for data analysis.Results During the past decade,ED visiting patients was increased significantly by 38.0% in 2014,compared with those in 2004,and the mortality was also increased accordingly from 0.7% in 2004, to 0.9% in 2009,to 1.2% in 2014 (P <0.01).Finally,a total of 1,091 deaths occurred in these three years were included for further evaluation.There were no significant changes in average age and gender distribution,and the average age was 61.9 and the male /female ratio was 1.36∶1 during past decade.The number of adults under 40 years old (18 -39)increased from 7.5% in 2004,to 10.6% in 2009,to 14.4% in 2014 (P <0.05).Both the facilities were upgraded and the number of staffs in ED increased markedly.The cardiovascular illness,cerebrovascular diseases,and sudden death were the leading causes of ED death during past decade.The incidences of trauma and tumor remained unchanged.Average time consumed from onset of illness to arrival to ED didn’t vary significantly during past decade.The study showed no changes in use of ambulance,but remarkable increases in number of non-compliant patients or their family from 18.3% in 2004,to 25.6% in 2009,to 38.3% in 2014 (P <0.01).The percentage of patients in the night time was higher,but there were no significant changes in number of emergency patients in the night time and during holidays in the past decade,but the mean ED stay time increased obviously from 22.4 h in 2004 to 53.3 h in 2014 (P <0.05 ).Conclusions During the past decade,although ED facilities and number of staffs have been improved apparently,ED mortality rate still keeps on escalating. The increase in ED mortality rate may be related to the severely ill patients presenting to ED,the obvious decrease in compliance of patients and the prolonged ED stay time.