Abstract: The liquid desiccant air conditioning system driven by natural cold source and solar energy regeneration is proposed. With temperature and humidity decoupled treatment,the air can be dehumidified without low temperature cold source. In this paper liquid desiccant system is adopted with natural deep well water as the cold source and solar energy as the regeneration of dilute solution. Based on analysis of a four-floor complex building in Qingdao adopted fan coil units and fresh air system,the energy consumption of the common vapor compression refrigeration and the liquid desiccant air conditioning system was calculated and compared. The calculation results show that the energy saving of the liquid desiccant air conditioning system can reach about 29.65%. The energy consumption of the air conditioning system is greatly reduced.