Background:The study was to explore the causes of high inpatient expenditure through analyzing the distribution characteristics as well as the influence factors of high inpatient expenditure cases during 3 years within a Grade-A tertiary hospital through various aspects and multiple angles,thus identifying the major influence factors for high medical expenditure to develop further research.Methods:We retrospectively studied 204l inpatient cases which cost more than RMB 100,000 Yuan per case in a Grade-A tertiary hospital from 2013 to 2015.We analyzed the compositions of the medical cost to evaluate the major factors that cause the high inpatient expenditure.All the data and materials were collected from medical record system,and the statistical methods included t-test,variance of analysis,and multivariate linear regression.Results:The average cost of the 2,041 cases was RMB 152,173 Yuan for medicines and materials of medical costs,which respectively accounted for 33.03％ and 32.32％ of the total cost;and the average length of hospital stay was 28.39 days/person.Diseases of skeletal and muscular system,circulatory system,and tumor were the top three disease categories of high inpatient expenditure,which accounted for 39.00％,33.46％,and 18.03％,respectively.Complications,criticality of the disease,gender of the patients,the occurrence of death,and the excessive length of hospital stay all had great impacts on average medical expenditure,while age,hospital infection,and surgery showed no significant impact on average medical cost.Conclusions:The main factors for high inpatient expenditure included the inadequate use of high-value medicines and materials,lacking cost control measures within the hospital,the excessive length of hospital stay for inpatients,and the unnecessary treatment for the patients.