Irradiation technology uses high-energy rays to induce ionization effects in insect pests and microorganisms, leading to their death. It is widely used to protect stored agricultural products, for foodborne pathogen control, and to improve food quality. This review systematically summarizes the types and characteristics of radiation used, including gamma rays, X-rays and electron beams, and summarizes the physiological effects of irradiation on insect pests and microorganisms, including on the reproductive, digestive, and antioxidant enzyme, systems. Different insect pests and microorganisms, as well as pest developmental stages and physiological conditions, vary in their sensitivity to ionizing radiation. The effectiveness of irradiation also depends on the ambient oxygen concentration and temperature. This review provides guidance for the practical application of ionizing radiation to protect stored grain, and a theoretical basis for the development of novel, effective, and environmentally-friendly, integrated pest management strategies.