Abstract: The phenomenon of heating non-uniformity widely exists in microwave heating applications. For low-loss media, microwave heating has the disadvantage of low heating efficiency. In order to solve these problems, this paper proposes a new type of periodic metal array which has reconfigurable transmission electric fields to improve the performance of heating common lossy media and low-loss media effectively. By controlling the On/Off state of PIN diodes on the array, the electromagnetic wave transmission of the metal array is changed to regulate the electric field distribution in the microwave cavity. The On/Off state matrix for PIN tubes is established to study the microwave heating effects of different heating objects. The numerical multiphysics calculation shows that the proposed structure can improve the uniformity and efficiency of heating microwave for common lossy media by 65.1% and 120.7%, respectively, and the heating efficiency of low-loss media can be improved by 91.2%. This method with low cost and simple control has great potentials in the industrial application of microwave heating.