In order to understand the development trajectory， policy focus and policy exploration and adjustment direction of China’s medical security system， based on the grounded theory， with the help of NVivo12 software， this study used a combination of qualitative and quantitative methods to analyze the medical insurance related policies issued by various national departments from 2009 to 2020. The study took the time when the National Healthcare Security Administration was established in May 2018 as the dividing line to classify policy documents into two stages for open coding. The results showed that after three?level open coding， 91 concepts and 26 categories were extracted from the policy texts from January 2009 to May 2018， and 92 concepts and 29 categories were extracted from the policy texts from June 2018 to December 2020. Comparing the open coding results of the two stages， and sorting and analyzing them from the category level and the conceptual level， it can be found that the average annual number of policy releases after the establishment of the National Healthcare Security Administration was 3.2 times larger than that of the previous ones. Policies in the following three areas have been significantly adjusted compared with the previous ones， i.e. “supply?side reform of medical services”“medical security public management services” and “reimbursement guarantee mechanism”.