Simulation is a effective technique which can be serves to evaluated the manpower allocation in maintenance field. The main aim of this research is to determine the suitable numbers of the “17” service stations under the present maintenance management conditions. The service station under the study is a SURAWONG exchange. This thesis has been demonstrated the procedure to formulated the number of service station. Then, the simulation model in STMAN is developed for the evaluation of operation performance of the service station under the present maintenance management. Input data such as the failure rate, type of failure, delay time and repair time have gotten from past historical data and standard of the TOT.