Taking the hotel as an example, analyses the characteristics of energy consumption in existing star hotels in south China based on the existing energy consumption data. Finds that the energy consumption of HVAC system is the largest part, accounting for about 66.9% of the total routine energy, in which the energy consumed by the chillers is the largest part, accounting for 49.66%, and followed by the air-conditioning terminal devices (AHU, PAU, FCU), 25.54% and the water pumps, 14.39%. Puts forward some countermeasures for energy efficiency reformation appropriately, including applying higher-efficiency chillers, large chilled water temperature difference (8 ℃), frequency control for chilled water and cooling water pumps, variable air volume control for fan coil units with brushless DC motors, higher-efficiency fans and air handling units, and higher-efficiency and double operating mode water-water heat pump heat recovery hot water system. Discusses feasibility and effects of these countermeasures one by one. And obtains the energy saving goal of HVAC system reformation after analysing energy-saving effects of each part in HVAC system.