Abstract: Demanding of higher temperature and humidity control accuracy, low humidity load and large thermal/humid ratio are the characteristics of air conditioning in cigarette manufacturing and it is typical of air conditioning system to keep the temperature of chilled water supplying at 7℃. The working status of air conditioning system in Guiyang Cigarette Factory in summer was tested. When chilled water temperature was raised from 7 to 12℃ step by step, the indoor air temperature and humidity were both within the required range, which indicated that it was feasible to raise the chilled water temperature, and it was proved that the coefficient of performance of chiller was increased by raising the chilled water temperature at the same load rate. According to the partial load performance of chiller, the running conditions of several chillers were optimized and the energy efficiency of chillers was obviously improved; when chilled water temperature was raised to 12℃, the energy saving of chiller station and air conditioning system reached up to 28% and 36%, respectively.