The invention discloses a top electrode structure of a bulk acoustic wave resonator and a manufacturing process, and the manufacturing process comprises the steps: preparing a substrate with a cavity,and sequentially manufacturing a bottom electrode layer and a piezoelectric layer, which cover the cavity, on the substrate; manufacturing a dielectric isolation layer on the piezoelectric layer, sothat the dielectric isolation layer covers part of the upper surface of the top of the piezoelectric layer; and manufacturing a top electrode layer on the dielectric isolation layer and the piezoelectric layer, the dielectric isolation layer being covered with the top electrode layer, and at least one side of the top electrode layer extending to the edge of the projection area of the cavity on thepiezoelectric layer. The dielectric isolation layer enhances the mechanical reliability and used for buffering when the stress change of the device layer is increased, and parasitic and reflected transverse waves of radio-frequency signals can be reduced. The mass load layer can form abrupt change of acoustic impedance at the edge of the top electrode layer, increase impedance of the parallel resonator, greatly weaken parasitic resonance, reduce pseudo-resonance and achieve the purpose of improving Q value.