A microwave rotary joint comprises a mode converter for converting microwave signals of a TE01 circular symmetric mode, and the mode converter comprises: two circular waveguides, one end of each of the waveguides has a circular input/output port; and two power dividing structures, each of the power dividing structure has an input/output port and four connecting ports, the four connecting ports are separated and surround each of the circular waveguides and connected to the inside of each of the circular waveguides, the two circular waveguides are integrated as one member through rotating a bearing.