Abstract: To improve the performance of internally cooled and pre-cooled liquid desiccant dehumidification systems in industrial deep dehumidification, a numerical model was developed for the pre-cooled type and validated using experimental data. The model error was within 10%; In parallel, experimental tests were carried out on the internally cooled liquid desiccant dehumidification system. Using ionic liquid and lithium chloride solution as working fluids, the deep dehumidification performance of different systems and solutions is compared and analyzed, and the system improvement direction suitable for deep dehumidification scenarios is proposed. The results show that with the increase of environmental moisture content, the outlet moisture content of the system increases and the latent heat energy efficiency increases. Under the same area, when the inlet moisture content is 18 g∙kg⁻¹, the outlet moisture content of the internal cooling system is 3.5 g∙kg⁻¹ lower than that of the pre-cooling system, and the COP is increased by 22%. The advantage of deep dehumidification energy efficiency is significant. Under the same volume, the COP of the internal cooling system is equivalent to that of the pre-cooling system, but its heat and mass transfer area is only one tenth of that of the pre-cooling system. Improving the heat and mass transfer area per unit volume is the key to strengthening its performance. When the inlet moisture content is 13 g∙kg⁻¹, the ionic liquid internal cooling and precooling systems can dehumidify to 5.5 g∙kg⁻¹ and 3.8 g∙kg⁻¹, respectively, which can meet the industrial deep dehumidification index of 6 g∙kg⁻¹. In addition, it is found that lithium chloride solution has a crystallization risk during deep dehumidification, while ionic liquids have no crystallization or corrosion risks. It is more suitable for the long-term stable operation requirements of industrial deep dehumidification, and is of great significance for reducing building energy consumption and achieving green construction.