The invention discloses a preparation method of a loudspeaker module, which comprises the following steps: S1, forming an enclosing structure on a metal upper shell, so that the enclosing structure encloses a cavity on the metal upper shell, and the enclosing structure is provided with a sound outlet for communicating the cavity with the outside; S2, forming a plastic support on the metal upper shell and located in the cavity, wherein the plastic support comprises a sound outlet part arranged at the sound outlet and a supporting part used for supporting the loudspeaker single body, and a sound outlet hole is formed in the sound outlet part; S3, installing a loudspeaker monomer on the supporting part, and enabling the metal upper shell, the plastic support and the loudspeaker monomer to form a front sound cavity communicated with the sound outlet hole in an enclosing manner; and S4, installing the metal lower shell on the metal upper shell, so that the metal upper shell, the plastic support, the loudspeaker monomer and the metal lower shell form a rear sound cavity. The plastic support is accommodated by the metal upper shell and the metal lower shell, maximization of the cavity space of the front vocal cavity and the rear vocal cavity is realized in a limited space, and improvement of the cavity performance is facilitated.