Heat stress is a general term for a series of physiological, biochemical, and behavioral adaptive responses caused by prolonged exposure to high-temperature environments. Severe heat stress can lead to multiple organ damage or even life-threatening consequences. China has a vast territory covering large areas with high temperature and high humidity. With the intensification of global climate warming, the impact of heat stress on the public nutritional health of populations in specific regions has become increasingly prominent. Natural plant resources are widely used in traditional diets for the prevention and treatment of heat stress. Their extracts show broad prospects in the development of such functional foods due to their advantages of safety, nutrition, and multi-target regulation. Therefore, based on a systematic review of the main damage mechanisms of heat stress on the body, this paper summarizes and analyzes the active ingredients of plant extracts with heat stress prevention and treatment functions and their key mechanisms of action. On this basis, key challenges in the development of functional foods from plant extracts are analyzed, including the stability of active ingredients, food processing difficulties, and the lack of standardized quality control systems. Future development directions are proposed in terms of formula synergy, formulation design optimization, and standardized quality control methods, aiming to provide theoretical references for the future research and development of functional foods for heat stress prevention and treatment.