Microwave heating has vast applications in the field of food processing due to fast heating rate and ease of operation. Although there is an increasing focus on microwave heating; non-uniform heating is still one of the major drawbacks. Various solutions to overcome non-uniform temperature distribution during microwave heating of food materials are proposed. In this article; the development of microwave heating technology in the food industry is reviewed; the fundamentals of microwave heating are illustrated; and the dielectric properties of food and penetration depth are also presented. Then the phenomena of uneven temperature distribution during microwave heating are presented according to different food materials. The method of improving uniformity is summarized in the areas of heating device design; food properties adjustment; processing optimization and package design. In the final section; the trends on improving the uniformity during microwave heating are proposed.