In order to study the amplification effect of multi-layer graphene on surface acoustic waves, the variable conductivity of graphene carriers was analyzed under an external electric field, and the amplification performance of multi-layer graphene surface acoustic wave amplifiers was studied under different substrates. The graphene surface acoustic wave amplifiers with ZnO and CdS substrates were compared and studied, and their magnifications under different carrier drift speeds were studied respectively. The results showed that, with ZnO as the substrate, when the carrier drift velocity was larger than and close to the surface acoustic wave phase velocity, the amplification performance was the best, and α could reach 34.92 dB.