Abstract: When the electron accelerator irradiates the wires and cables, especially large size wire and cables (the outer diameter is 40-80 mm), the irradiation is often uneven. The difference between the maximum and the minimum thermal elongation is far more than 1.5 times, or the inhomogeneity is far more than 20 percent. In order to improve the irradiation uniformity of cables, reflection magnet is used to supplement and perfect the irradiation process of electron accelerator.This paper mainly analyses the causes and solutions of the non-uniform phenomenon in the irradiation processing of wires and cable, introduces the working principle and application method of reflection magnet, and compares the effects of using reflection magnet and not using reflection magnet to irradiate wires and cables. The irradiation results show that the irradiation uniformity of large size cables can be improved by using reflection magnets, which can provide reference for improving the irradiation uniformity of large size cables.