Data centers are essential infrastructures for various IT services. As the number of IT servers increases, global data centers consume 1,002 billion kWh of electricity annually. The cooling systems of data centers accounts for approximately 30–40% of the power consumption. Free cooling systems have been increasingly used to reduce the power consumption of data centers, and various such systems have been proposed to further improve efficiency. However, the performance of the cooling towers of the free cooling systems are limited during summer caused by to hot and humid environments. This limitation minimizes the temperature drop of the coolant, even if it exhibits effective cooling effects during winter. To overcome this limitation, this study proposed a liquid desiccant cooling system that improves the performance of the cooling tower by lowering the wet bulb temperature of ambient air and reduces the energy consumption of the chiller. The proposed liquid desiccant cooling system is a method that lowers the wet bulb temperature of outdoor air using the difference in the partial pressures of water vapor as high-temperature and humid outdoor air passes through an absorber during summer. Additionally, the heat of condensation generated in the condenser is recovered and used as a heating source for regenerating an aqueous solution to achieve more energy savings. This method eliminates additional regenerative heat sources. An experiment was conducted using EES simulation to investigate the effects of the proposed LD cooling system under various environmental conditions, including the subtropical climate of America, the temperate climate of the Republic of Korea, and the tropical climate of Vietnam. The proposed LD cooling system successfully lowered the wet bulb temperature of the outdoor air and improved the performance of the cooling tower. The results show that the proposed LD cooling system reduced the energy consumption by 35.68% under the temperate climatic conditions, 26.59% under the subtropical climatic conditions, and 26.31% under the tropical climatic conditions. This confirms that the proposed LD cooling system is beneficial for data centers built in subtropical, temperate, and tropical climates.