The invention relates to a preparation method of a capacitive-type silicon microphone. The preparation method of the capacitive-type silicon microphone comprises the following steps of: providing a substrate which is provided with a circuit region at least comprising a passivation layer distributed vertically, a device group and a medium layer, wherein the passivation layer is the surface layer of the circuit region; the medium layer is arranged below the passivation layer, and the device group is embedded on the bottom of the passivation layer, and comprises a first device and a second device; depositing a sacrifice layer at the circuit region; patterning the sacrifice layer so as to define an air gap region; depositing a metal layer on the circuit region so as to enable the metal layer and the second device to be connected; forming at least one release hole by a patterning method, wherein the release holes run through the metal layer; etching the sacrifice layer, the passivation layer and the medium layer so as to form air through holes in one-to-one correspondence to the positions of the release holes by taking the metal layer as a mask; and etching the circuit region, removing the sacrifice layer so as to form an air gap, and etching continuously into the substrate so as to form an air cavity. The technology is simple in process, and is low in production cost.