Compared with conventional air-conditioning condensation, the liquid desiccant dehumidification system has the advantages of high efficiency, independent control of temperature and humidity, flexible dehumidification, and energy saving. It can play a great advantage in the area of high temperature and humidity. To improve the comprehensive performance of liquid desiccant dehumidification system is one effective way to solve high humidity in extreme hot and humid climate area. In order to study how liquid desiccant dehumidification system can improve the recyclable duration and system performance by optimizing the circulation structure, Yongshu Island is taken as an example to analyze operation parameters and combined circulation mode of adiabatic cross-flow dehumidifier and regenerator. The optimal reflux ratio of solution dehumidification system with dehumidification self-circulation + interstage circulation mode (SD-SIC) is studied. The numerical calculation of the dehumidifier and regenerator model shows that: the optimal reflux ratio of the constant air volume SD-SIC system is 0.8, and the dehumidification/regeneration volume, dehumidification efficiency and total solution energy density at system equilibrium at this reflux ratio are: 4.69 g·s-1, 60.53 % and 72.85 kW·kg·s-1 respectively, which are 2.2 times, 1.2 times and 0.6 times that of the SD-IC system. Adjustment of the dehumidification reflux ratio can be used as an optimized air-flow matching method for the SD-SIC system at constant airflow conditions: Under constant airflow conditions, the dehumidification reflux ratio can be used to optimize the SD-SIC system towards the SD-IC system at the optimum flow rate matching and is more energy efficient than the SD-IC system. It can be seen that the SD-SIC system has good energy-saving q power and can provide a reference for the optimization of solution dehumidification system operation strategies in extreme hot and humid climate zones.