In order to effectively control the growth of medical expenditure, the medical insurance organizations adopted the Global Budget System. The Department of Health, Executive Yuan, to establish the basis of this payment system planned to adopt Diagnosis Related Groups on hospital medical expenditure. This study used system development tool, Delphi, to build a ”Diagnosis Related Groups Decision Support System (DRGDSS)”, based on the medical information of inpatients with respiratory system diseases, to assist disease classifying coding personnel. The results showed that using the DRGDSS enhanced the effectiveness of disease classifying coding and further led to correct and reasonable medical reimbursement.