The present invention discloses a microwave detector and manufacturing method thereof and stray electromagnetic radiation suppression method, wherein the microwave detector includes a reference ground, a radiation source, a driving circuit, and at least a set of suppression fence posts. The driving circuit is electrically connected with the feed point of the radiating source, wherein the radiating source, the reference ground and the driving circuit are arranged in order along the thickness direction of the microwave detector. The radiation source and the reference ground are separated and spaced to form and define a radiating gap between the radiation source and the reference ground, wherein a spacing distance between the reference ground and the driving circuit is greater than or equal to 1/128λ, wherein λ is the wavelength of the radiated wave of the microwave detector. The set of suppression fence posts surrounds the driving circuit in such a manner that the suppression fence posts are respectively and spacingly arranged on the side portions of the driving circuit.