[Objective] This study aimed to investigate current issues, root causes, and improvement measures of the main diagnostic codes on the homepage of a hospital's inpatient medical records, and to improve the accuracy of the hospital's main diagnostic codes.[Methods]A retrospective analysis was carried out on the homepage data of inpatient medical records in a hospital. After implementing the quality control of medical record coding, we compared and analyzed 1000 medical records before the intervention (March 1 to June 30, 2020) and 1000 medical records after the intervention (March 1 to June 30, 2021). The accuracy of the homepage data of the medical records was compared and the quality control efficacy after the intervention was evaluated.[Results] Following the intervention, the number of major diagnostic errors on the homepage of medical records decreased by 84% (from 38 cases per 1000 to 6 cases per 1000, p<0.05). Among them, the main diagnosis error was reduced from 6 cases to 1 case, the main diagnosis selection error was reduced from 5 cases to 2 cases, the ambiguous (QY) medical records were reduced from 19 cases to 2 cases, and the medical records with codes not merged were reduced from 9 cases to 1 case. According to the analysis of influencing factors, after the intervention measures were taken, the filling errors by physicians decreased from 17 cases to 2 cases, the errors by coders decreased from 12 cases to 2 cases, and the errors from information management decreased from 9 cases to 2 cases.[Conclusions] After the intervention, the number of errors in filling by physicians, coding by coders, and information management on the homepage of medical records decreased significantly. In addition, the accuracy of the main diagnostic codes on the homepage has been greatly improved, which helps ensure the reliability of information statistics and effectively improves the quality and safety of medical care.