OBJECTIVE To evaluate the budget impact on medical insurance fund upon the treatment of pulmonary arterial hypertension（PAH）included in the outpatient special and chronic disease management policy （hereinafter refer to as the Policy ）， so as to provide reference for medical insurance reimbursement decision-making. METHODS Based on the perspective of medical insurance payer ，a budget impact model with 10 million people was built to calculate the budget impact on the medical insurance fund in the next three years （2021-2023）after PAH treatment included in the Policy. The measured cost mainly included the cost of medicine，outpatient registration ，examinations，hospitalizations，and death events. RESULTS A total of 34-36 patients with PAH per year were expected to use targeted therapy during 2021-2023. For cities with outpatient costs not covered by the pooling fund of basic medical insurance ，upon the treatment of PAH included the Policy ，the annual expenditure of the medical insurance fund increased by about 40 000 yuan，i.e. an increase of about 1 000 yuan per patient. For cities with outpatient costs covered by the pooling fund ，the annual expenditure of the medical insurance fund increased by about 80 000 yuan，which was equal to 2 000 yuan increase per patient. The increment of above cost decreased year by year. CONCLUSIONS The incremental expenditure of the medical insurance fund is controllable after the treatment of PAH included the Policy ；with the implementation of the Policy ，the incremental expenditure of the medical insurance fund will be reduced year by year.