The invention discloses a kind of high-power multi-channel microwave device, such as a harmonic suppressor, a power divider used for power synthesis, a combiner, an attenuator and the like. A microwave processing apparatus equipped with rectangular transmission lines is disclosed. The microwave processing apparatus comprises two sections of transmission lines (1) which are positioned at an input end and an output end respectively and have overlaid axial lines, at least two metal bodies A (2) which run through the surface of each section of the transmission lines (1), at least two signal channels (3), at least one metal ridge (4) which is positioned in each signal channel (3), or a series of metal bodies B (5), wherein the center of the axial line of the microwave processing apparatus equipped with the rectangular transmission lines can be divided into two sections; and other microwave devices which comprise a PIN switching tube, a PIN amplitude-limiting diode, a power amplifier and the like, are arranged between the two sections to form an amplitude limiter, an attenuator, a switch and power comparator and the like. The microwave processing apparatus is widely applied to radar, missile guidance and various mobile communication systems.