Nowadays, air-conditioning is steadily increasing from year to year. In 2012, the usage in Cambodia was only 77 thousand units, and in 2019 up to 134 thousand units. Variable refrigerant flow (VRF) was introduced in 1982, and the Water-cooled chiller was patented by an inventor named Willis Carrier in 1921. In this work, the objective aims to evaluate the cooling load and study the techno-economic of VRF and Water-cooled chiller of the Ministry of Tourism in Sihanouk province as a case study. Before getting the accurate techno-economic related to operation costing, investigation costing, and maintenance costing, heat calculation in the building is the most important parameter. Heat calculation was applied to manual calculation, estimation calculation, and HAP software. After getting the heat total, the methodology has been explored through the internet and secondary data from relevant published academic literature from journal articles and research papers. The data collected in the qualitative research are the data that comes from a direct survey of air-conditioning companies. In the building, the investigation costs of VRF and water-cooled chiller are 89759$ and 120369$.The operation cost of VRF in 1 year is 5158$ and the operation of water-cooled chiller in the same 1 year is 5017$. The maintenance cost of VRF is 620$ for every six months spent on cleaning air-conditioning and gas recharging. For the water-cooled chiller, the maintenance cost is related to cooling tower, AHU system, and chilled water pump, which costs 1500$. In conclusion, a water-cooled chiller has a lot of components and it is more expensive and requires much budget than a VRF system. For recommendation, for the small office, school or small building we should better use VRF system and for the larger commercial building we should use water-chiller it is profitable.