In Bangladesh, CNG (compressed natural gas) is used in public transport in a large extent for its availability, cheapness and environment friendly. Though at first time CNG was used in only three wheelers, recently it has been used in all type vehicles like bus, truck, car, etc. The hike in prices of other fuels increases the uses of CNG in vehicles. The number of CNG driven vehicles is increasing significantly. Simultaneously, CNG refueling stations are also increasing quite proportionally across the country. In this paper a simple model for estimation of CNG demand for public transport and of refueling stations in a metropolitan city has been developed. The results generated from this model have been justified by the key performances of selected CNG stations using the computer based... ARENA software. For this purpose, the whole City and nearby areas are divided into three distinct zones. Then the consumption of CNG by inner vehicles (refuels CNG and run within city) and outer vehicles (refuels CNG from city, but run outside of the city) of the Sylhet City have been estimated. Using this estimation, the required numbers of CNG refueling stations for each zone are calculated based on the developed model. The computational results depict that there are excess refueling stations in the city and most of them are under-utilized. The developed model can be used to determine the optimum number of refueling stations in any metropolitan city. Finally, an improved system of a CNG station has been proposed using an ARENA model to improve its overall key performances.