Provided are a MEMS microphone and a formation method thereof. The formation method comprises: providing a first substrate comprising a first surface and a second surface, wherein, the first substrate comprises at least one conductive layer, which is located at a side of the first surface of the first substrate; providing a second substrate comprising a third surface and a fourth surface, wherein, the second substrate comprises a second base and a sensitive electrode, and comprises a sensitive area, in which the sensitive electrode is located at a side of the third surface of the second substrate; fixing the first surface of the fist substrate and the third surface of the second substrate each other; thereafter, removing the second base, and forming a fifth surface opposite to the third surface of the second substrate; forming an empty cavity between the first substrate and the sensitive area of the second substrate; and forming, from a side of the fifth surface of the second substate, a first conductive plug penetrating to the at least one conductive layer. The MEMS microphone is improved in performance and reliability, is reduced in size, and is lowed in process cost.