Abstract: In order to eliminate the "cold-heat offset" and reduce the high energy consumption for reheating in the air conditioning system with conventional air recycling technology, an independent fresh air system based on 2-temperature cooling water unit was designed for the major production building of Guiding Cigarette Factory. The software DeST (Designer's Simulation Toolkit) was used to analyze the heat and cold loads in a full year, emphatically the load in summer, the load was divided into indoor load, fresh air load and reheated load. The independent fresh air system, includes a high-temperature chiller to provide 16-20℃ chilled water for cooling indoor recycling air; and a conventional chiller to provide low temperature (7℃) chilled water for cooling and dehumidifying fresh air. The fresh air is used to deal with indoor humidity so as to control indoor temperature and humidity separately. A comparison test was conducted between the air conditioning systems with conventional recycling air technology and with independent fresh air system. The results showed that:1) Independent fresh air system reduced the equivalent reheated cold load by 27.6% and the reheating energy consumption by 1 449 kW. 2) Compared with conventional chillers, the energy saving rate of the 2-temperature cooling water unit was 37.3% in summer. This technology provides a support for the energy saving and emission reducing of cigarette factories.