The present application provides a gas showerhead including a gas distribution and diffusion plate and a water cooling plate, the gas distribution and diffusion plate includes several columns of first gas diffusion passages connecting to a first reactant gas source and several columns of second gas diffusion passages connecting to a second reactant gas source; the water cooling plate having cooling liquid passages is arranged below the gas distribution and diffusion plate, and the water cooling plate is provided with first gas outlet passages provided for the reactant gas in the first gas diffusion passages to flow out and second gas outlet passages provided for the reactant gas in the second gas diffusion passages to flow out, so as to isolatedly feed at least two reactant gases into a reaction chamber.