As a key link to guarantee food quality and security, food drying is of great significance to realize sustainable agricultural development. At present, the global food demand is rising, the production scale is expanded, and the traditional single heat source drying technology is difficult to meet the large-scale fast drying demand due to high energy consumption, serious waste heat, low efficiency and other problems. This paper focuses on the research of waste heat recovery and dual heat source technology in the process of grain drying to improve grain drying efficiency, reduce energy consumption, reduce environmental pollution and promote the sustainable development of grain drying technology [1]. Research and design efficient waste heat recovery system, convert waste heat in drying process into recyclable heat energy, integrate hot air and hot water dual heat source technology, optimize heat transfer and control, and develop intelligent control system to monitor and adjust drying parameters in real time, so as to achieve efficient and stable drying. The prototype test shows that the system can operate stably under different working conditions, the energy saving effect is obvious, and the drying quality is superior to the traditional process, which provides new ideas and methods for the upgrading of grain drying technology. In the future, advanced sensors, big data analysis and artificial intelligence technologies can be further combined to improve the intelligent level, develop energy-saving and environment-friendly dryers, accelerate the integration with other agricultural equipment, and promote the agricultural modernization process.