The Ohm´s Law in solution considering the gas and liquid distribution in porous electrodes is given. Based on the mathematical model of the single pore electrode, the effective three-phase boundary length of the electrochemical reaction is defined and calculated. One-dimensional current and overpotential mathematical model of the porous electrode process is also established by the gas and liquid distribution theory of the porous medium. Current and overpotential distributions along normal direction of the electrode are given by numerical iteration method. Influence of the gas saturation and effective three-phase boundary length to the current and overpotential distributions are discussed.