［［Objective ］］ This study aimed to solve coking scorch caused by excessive local temperature often occurs when microwave heating of fruit and vegetable materials.[Methods ] A coupling model of electromagnetic -heat conduction with dielectric properties varying with temperature was established,and the correctness of the model was verified by experiments.[Results ] When the shape is cube,materials with larger dielectric properties are more likely to form a high temperature accumulation zone far from the center,and when the shape is sphere,materials with larger dielectric properties are more likely to form a high temperature accumulation zone in the center.If the size is the same,the temperature uniformity of the material with smaller dielectric properties is higher,and the temperature uniformity is increased by 43.8% when the dielectric constant is reduced by 24.8%.[Conclusion ] The temperature distribution uniformity of the material can be effectively controlled by adjusting the dielectric characteristics and size of the material.