Asymmetric electrochemical capacitor was categorized into two types: a battery-type electrode|capacitor-type electrode capacitor and a capacitor-type electrode|capacitor-type electrode capacitor. When designing asymmetric electrochemical capacitor, the influences of both current density and the electrode's potential window were taken into account. This article analyzed how the mass ratio between two electrodes influenced the electrochemical performances of asymmetric electrochemical capacitor. The formulas describing capacitor performance parameters (work voltage, specific capacitance, energy density and power density) were derived and applied to two types of asymmetric electrochemical capacitors. Therefore, the concrete relationships between mass ratio of electrodes and capacitor parameters were obtained. The influence of current density on mass ratio was investigated with organic LiMn2O4/AC system and others.