Based on ideal financial operation of medical payment of National Health Insurance (NHI), the Global Budget System promoted the efficiency and quality by the medical professional review for the mediation approval of the medical expenditure cases. This study was set up to assess the reimbursement disputes by legal evaluation, and focused on those disputes about the payment subtraction of high-priced drugs by the regulating review based on the Reference List for Drug and the Fee Schedule for Medical Service of NHI Act. This study concluded that, because of the non-relevant consideration, the review regulation, mentioning about the payment subtraction under ”Code 323A: High-priced Drugs” lacked the legal clarity, and would lessen the contribution of medical professional review system and influence the healthcare quality of NHI. Besides, the Guideline of Coding System of Payment Subtraction on Professional Review was technical and critical for the medical professional reviewers, and was non-regulating. It was not a kind of the ”administrative rule” used in the Administrative Procedure Act, but just a kind of ”peer constrain.” Finally, this study recommended to develop a special pharmacoeconomic council to set up a prediction model by adjusting the related parameters to moderate the growth on NHI expenditures after the definition of ”High-priced Drugs.”