Background:With the rising incidence as well as the medical expenditure among patients with unstable angina pectoris,the research aimed to investigate the inpatient medical expenditure through the combination of diagnosis-related groups (DRGs) among patients with unstable angina pectoris in a Grade A tertiary hospital to conduct the referential standards of medical costs for the diagnosis.Methods:Single-factor analysis and multiple linear stepwise regression method were used to investigate 3933 cases between 2014 and 2016 in Beijing Hospital (China) whose main diagnosis was defined as unstable angina pectoris to determine the main factors influencing the inpatient medical expenditure,and decision tree method was adopted to establish the model of DRGs grouping combinations.Results:The major influential factors of inpatient medical expenditure included age,operative method,therapeutic effects as well as comorbidity and complications (CCs) of the disease,and the 3933 cases were divided into ten DRGs by four factors:age,CCs,therapeutic effects,and the type of surgery with corresponding inpatient medical expenditure standards setup.Data of nonparametric test on medical costs among different groups were all significant (P ＜ 0.001,by Kruskal-Wallis test),with R2 0.53 and coefficient of variation (CV) 0.524.Conclusions:The classification of DRGs by adopting the type of surgery as the main branch node to develop cost control standards in inpatient treatment of unstable angina pectoris is conducive in standardizing the diagnosis and treatment behaviors of the hospital and reducing economic burdens among patients.