Objective: Through the analysis of the basic situation of the medical service of the psychiatric inpatients in Beijing from 2003 to 2015, this study provides the basis for rational allocation of mental health resources and reasonable utilization of medical expenses. Methods: Descriptive statistical method was used to analyze the annual discharged patients, average hospitalization days and hospitalization expenses of inpatients with mental illness. Results: The annual discharged patients were increasing gradually. The number of discharged patients increased from 7861 to 24898. The annual average growth rate was 10.08%. The average length of stay in hospital since 2011 was lower than before, which were about 40 days in recent years. The average hospitalization expenses per day were also increasing. It increased from 131.04 yuan to 461.02 yuan. The annual average growth rate was 11.05%. Conclusion: The demand of mental illness patients for hospitalization is gradually increasing, and the medical burden is heavier than before. It is essential to adjust the pay policy to promote the rational and effective use of medical expenses