The invention discloses a method for matching a microstrip-waveguide conversion probe and impedance, which belongs to the technical field of electromagnetic fields and microwave circuits. The method comprises: designing and obtaining the size of the conversion probe according to the back-to-back structure of the microstrip-waveguide conversion probe; placing a micro strip in the middle of the back-to-back structure of the microstrip-waveguide conversion probe; performing computer simulation on the width of the conversion micro strip, and obtaining the input impedance of the conversion probe; and utilizing a one-fourth wavelength impedance conversion line to match the input impedance into 50 ohms. The method combines design of the size of the conversion probe and impedance calculation, namely impedance matching design is completed when the microstrip-waveguide conversion probe is designed, conveniently obtains the input impedance of the conversion probe, and further realizes design of a matching circuit. Moreover, the method is simple to operate, has simple and convenient process, simplifies the matching circuit, and improves the precision of impedance matching.