The invention relates to an electrolyte for a dual-layer capacitor and the dual-layer capacitor. The electrolyte for the dual-layer capacitor comprises an electrolyte and a nitrile organic solvent, wherein the electrolyte is selected from a combination of one or more of the following structural formulas, the structural formulas is shown as specification, and A is N or CH. By improving the electrolyte, the electron transmission rate of the electrolyte under a large current is improved, so that the working voltage of the dual-layer electrolyte fabricated from the electrolyte can reach 2.8-3.2V, and the indexes such as static capacitance, the power density and the cycle property can be greatly improved.