The QOS(Quality of Service) recognized by the customer will become the most important thing under the competitive telecommunications market. Korea Telecom is going to develop many system to manage the telecommunication network, to improve the level of QOS, and to increase the revenue. Operation and Maintenance Adiministration System is one of the systems developed to meet those purposes efficiently. This system gathers qualities data from telephone offices or operation centers and analyze the results of QOS improvement activities and evaluate overall QOS. And also system makes it possible to improve the cost/effectiveness of operation and maintenance of telecommunication network. Operation and Maintenance Administration System has four functional modules, i.e., the user interface module, the database management module, the QOS management module, and the database conversion module. The purpose of this study is to develop the QOS management program, one of the four functional modules of the system,using FOCUS 4GL/DBMS. Since Operation and Maintenance Administration System is developed using FOCUS 4GL, every user can handle and maintain the system very easily and reduce system backlogs.