Abstract: Rapid advancement and widespread deployment of deep and ultra-deep wells in major oilfields, both domestically and internationally, have highlighted the challenges of elevated downhole temperatures in modern drilling operations. These extreme thermal conditions considerably threaten the stability, functionality, and reliability of drilling fluids that are essential to successful drilling. High downhole temperatures alter the chemical and physical properties of the drilling fluids, compromising their performance in maintaining wellbore stability, transporting cuttings, and lubricating the drill string. Addressing these challenges has become a key focus in petroleum engineering. Researchers globally are actively developing and refining various cooling technologies to regulate drilling fluid temperatures. These technologies include natural cooling, forced cooling, and the use of low-thermal-conductivity drilling tools, all aimed at enhancing the thermal resistance of drilling fluids under high-temperature conditions. This study presents a analysis of the impact of elevated downhole temperatures on both drilling fluids and drilling tools employed in deep and ultra-deep wells. This paper examines the detrimental effects of extreme temperatures on the chemical and rheological properties of drilling fluids, such as viscosity and density, which undermines their efficiency in critical functions. Concurrently, high temperatures exacerbate the wear and failure of drilling tools, adversely affecting the efficiency, safety, and cost-effectiveness of drilling operations. In addition, this study explores the heat transfer mechanisms between drilling fluids and geological formations, shedding light on the dynamic interactions that influence thermal behaviors within the wellbore environment. Such insights are essential for the development and implementation of effective thermal management strategies in drilling. Furthermore, this study provides a systematic review of current domestic and international research on drilling fluid cooling technologies, categorizing them into three primary strategies. The first strategy involves regulating the temperature of drilling tools at the surface and downhole through the integration of advanced cooling systems and thermal optimization of drilling equipment. The second strategy focuses on enhancing the composition and thermal properties of drilling fluids, such as density and thermal conductivity, to improve their performance in high-temperature environments. The third strategy emphasizes the development and application of innovative cooling materials and technologies to increase heat dissipation efficiency in drilling fluids. Despite these advancements, significant challenges remain. Current cooling technologies are often hindered by high costs, limited efficiency, and difficulties in adapting to the complex and dynamic conditions of deep and ultra-deep wells. This study highlights these limitations and emphasizes the pressing need for innovative, cost-effective, and adaptable solutions to address these challenges. Future advancements in drilling fluid cooling technologies should focus on developing low-cost, high-efficiency, and intelligent thermal management systems. These systems must enable precise temperature regulation and adapt seamlessly to diverse operational conditions, providing robust support for the safe, efficient, and economical drilling of deep and ultra-deep wells. By aligning with the industry’s growing demand for sustainable, intelligent, and technologically advanced solutions, these innovations have the potential to considerably enhance the performance of drilling fluids in high-temperature and ultra-high-temperature environments while fostering advancements in related industries.