A microwave heating device with reflection protection belongs to a technical field of microwave applications. A first port of a circulator is connected to a microwave generator, and a second port of the circulator is connected to a microwave transmission device. A water load comprises a waveguide section, a metamaterial structure layer and the absorption tube. One end of the waveguide section is connected to a third port of the circulator, and the other end is sealed by a metal plate. The metamaterial structure layer is arranged in the waveguide section, and a center of the metamaterial structure layer has an accommodation space. The absorption tube is arranged along an internal wall of the accommodation space with a spiral extending form. Both ends of the absorption tube penetrate the waveguide section, and coolant flows in the absorption tube. Relative dielectric constants of the metamaterial structure layer gradually increase.