In order to get the theoretical reference for making high efficiency porous electrode, microscopic mechanism and macroscopic phenomena of the porous electrode reaction were explored by new ideas and new methods. The superiority of the vertical porous gas electrode to the traditional electrode was proved by the zinc-air battery discharge experiment. By the experiment, three macroscopic time-varied courses of the three-phase interfaced shape variation were observed. According to electrochemical processes corresponding to the three macroscopic courses, two kinds of typical three-phase interface formed in the electrode reaction were defined. The microscopic mechanism of the electrolyte movement in the porous electrode was analyzed. It was concluded that the ideal discontinuity interface is the optimal active state of the gas porous electrode.