Objective To analyze the situation and changing trend of free medication service in Beijing from 2013 to 2020, and to propose policies and service improvement measures. Methods A retrospective survey was conducted in Beijing to collect and analyze the service subjects, service process, drug catalog, fiscal investment and patient participation of free medication in each district in recent years. Results Among the 16 districts of Beijing, 81.25% of the districts included the patients listed in Item (2) of Paragraph 2 of Article 30 of the Mental Health Law into the scope of free medication, and 75% of the districts broke the restriction that the service targets were registered residents in Beijing. 56.25% of the districts provided a variety of free medication modes, and 81.25% of the districts provided a mode of nearby community service. The catalog of free medications in various areas was still based on the Beijing catalog, and only 18.75% of the districts supplemented the list. In 2020, the total investment of free medicines and subsidies was 88.3768 million RMB, and the per capita investment was 1 616.02 RMB. The total cost showed an increasing trend year by year. From 2013 to 2020, the difference of per capita annual financial investment in drugs and subsidies was statistically significant (F=9.248, P<0.001). The per capita cost basically showed an increasing trend year by year except for individual years. In 2020, 54,688 patients participated in the free medication service in Beijing, and the participation rate was 67.23%. From 2013 to 2020, the difference of annual participation rate of patients was statistically significant (χ²=37098.759, P<0.001), and the number and proportion of patients increased year by year. Conclusion The practice of the district level has proved feasible to expand the scope of free medication service and to optimize the service process, which should be paid more attention in the future. With the continuous advancement of policies and services, the level of patient participation in various areas will tend to be relatively balanced after rising year by year.