Abstract: In order to solve the cooling problem for greenhouse in the humid and hot area in summer, liquid dehumidifying and cooling system with CaCl2 liquid was proposed. Under the condition that the dehumidifying and cooling system was operated in greenhouse, the experimental target about the relative humidity of the air on the spray room exit was determined, and the factors affecting on the experimental indexes were analyzed, such as inlet air flow, liquid desiccant flow concentration and temperature, inlet air temperature and humidity and so on. By the single factor and multi-factor orthogonal experiment, when the system was operating, the significant factors included desiccant concentration and temperature, inlet air temperature and humidity. Through the regression analysis, the mathematical model of spraying and dehumidifying with CaCl2 was established and verified, and the maximum relative error of model was less than 5%. This paper provides a reference for greenhouse cooling under high temperature and high humidity condition in summer in the South China.