The technology of liquid desiccant and solar regeneration, is the key technical problems of evaporative cooling in high temperature and humidity region. Through the experimental measurement, study the relationship between the flow-ratio of air and solution and the dehumidify capability in different operating point of calcium chloride (CaCl2) and chloride lithium (LiCl) mixture liquids. Also analyze the effect of the heat capacity ratio (m ) and total thermal efficiency according the total thermal efficiency count formula. The conclusion is that not the more air flow, the better dehumidification efficiency, when the solution mass flow is consent. The flow-ratio of air and solution need be optimized. The dehumidification efficiency of mixture salt solution in the solar dehumidification system was improved from percentage of 32.5 to 51.7, according to the optimal the flow-ratio of air and solution. This research for improving the dehumidification efficiency of mixture salt solution in the solar dehumidification system provides the theory evidence.