Microwave oven, rectangular waveguide and determination method thereof

A microwave oven, a rectangular waveguide and a determination method thereof, relating to the field of home appliances. The length of a long side Wlength of the rectangular waveguide (4) ranges from 65mm to 90mm, the length of a broad side a of the rectangular waveguide (4) ranges from 70mm to 90mm, the length of a narrow side b of the rectangular waveguide (4) ranges from 30mm to 44mm, and the distance Slength between the center of a microwave feed inlet (1) and a short circuit surface (3) of the rectangular waveguide (4) ranges from 25mm to 40mm, so as to reduce the loss of the microwave generated by a microwave source during transmission, thereby not only saving energy but also improving the efficiency of the microwave oven.