In line with the increase in the world population, natural gas, which has an increasing share in fossil fuels, is nowadays transported throughout pipelines in the form of liquefied natural gas (LNG) and compressed natural gas (CNG). Natural gas is preferred to be transported with CNG in terms of optimum cost. CNG is reduced to a volume of 1/250 at 200 bar pressure in filling facilities and is transported to multi-element gas containers or gas tankers where pipelines do not reach. Although the highest cost for these plants seems to be gas transportation costs, the design, infrastructure and operational gaps, especially in plant management of the filling facilities constitute the costs that are not significantly visible. In parallel with the costs incurred, in this study, a pre-cooling process was actively applied for cost-based improvement in a bulk CNG filling facility, while operational optimization was aimed passively. The filling process of the facility in 2016 was examined according to real data and pre-cooling was made in 2017 by adding a “chiller” to the filling process to increase the filling rate to tankers. Thanks to the precooling in 2017, the filling amount made to tankers increased by %7.23. In 2018, the filling process was analyzed in detail according to the data of 2017 and the factors affecting the filling rate were determined. According to these factors, the filling operation has been optimized on a cost basis. Filling operations in 2018 have been optimized for factors varying from month to month and even day, such as; temperature conditions, filling method, the structure of gas tankers and filling platforms, ie the effect of the material used, personnel effect and the filling rate of machines like chiller, compressor. After optimization, the amount of filling made in 2018 increased by %4.36 compared to 2017.