A wide-temperature-range electrolyte for super capacitors and a preparation method thereof are provided. The wide-temperature-range electrolyte comprises the following raw materials in parts by weight: 10-30 parts of solute, 20-70 parts of main solvent, 0.1-3.5 parts of solubilizer, 0.1-4.2 parts of dispersing agent and 0.1-4.0 parts of stabilizer. The prepared wide-temperature-range electrolyte for super capacitors can normally work within the wide temperature range of -40 DEG C to 115 DEG C. The viscosity of the electrolyte is lower than 100cP, the conductivity of the electrolyte is 2-13mS/cm, and the voltage window of the electrolyte can reach 1.5-3.2 V.