The invention discloses a dome applied to a diaphragm. The dome comprises a top composite layer, a bottom composite layer, and a middle substrate layer which is connected with the top composite layer and the bottom composite layer. The top composite layer and the bottom composite layer respectively comprise at least one metal layer and at least one ceramic layer. The metal layer is coated with the ceramic layer. The dome applied to the diaphragm can be combined on the diaphragm for realizing direct use. The upper surface and the lower surface of the middle substrate layer of the dome is coated with the composite layers which are respectively provided with metal and ceramic, thereby improving rigidity of the dome, keeping flexibility of the dome, effectively alleviating audio bandwidth attenuation of the diaphragm, realizing larger bandwidth, settling a high-frequency problem of a routine diaphragm and greatly improving audio output quality.