The present invention provides a semiconductor structure and a preparation method of a microphone comprising the semiconductor structure. The preparation method comprises the steps of providing a semiconductor substrate, and depositing a first silicon dioxide layer on the semiconductor substrate; forming a Ge filling layer on the surface of the first silicon dioxide layer, and forming lower electrodes in the Ge filling layer and the first silicon dioxide layer; depositing a second silicon dioxide layer and a third silicon dioxide layer on the surface of the Ge filling layer; forming an upper electrode on the surface of the third silicon dioxide layer; forming a silicon nitride layer with a sound hole and a blocking structure on the surface of the upper electrode; etching a through hole penetrating through the semiconductor substrate on the back; and removing the first silicon dioxide layer, the Ge filling layer, the second silicon dioxide layer and the third silicon dioxide layer. The Ge filling layer above the lower electrode is used as an etching blocking layer of the silicon dioxide layer, thereby preventing etching of the silicon dioxide layer from damaging the lower electrode. The Ge as the filling layer is easier to remove and leaves no residual on the surface of the lower electrode, so that the capacitance stability and sensitivity of the microphone are improved.