The invention discloses electrolyte of a high-voltage aluminum electrolytic capacitor. The electrolyte is characterized by comprising a main solvent, an auxiliary solvent, a solute and a spark voltage increasing agent, wherein the main solvent comprises one or more of ethylene glycol, gamma-butyrolactone, DMF and diglycol monobutylether; the auxiliary solvent comprises two or more of polyethylene glycol 200, polyethylene glycol 400, a nanosilicon dioxide solution, glycerol, propylene carbonate and ethylene carbonate; the solute comprises two or more of ammonium sebacate, ammonium adipate, adipic acid, boracic acid, ammonium pentaborate, ammonium azelate, ammonium dodecanedioate, ammonium formate, ammonium benzoate, mannitol, sorbitol, citric acid and quadrol. The electrolyte can be applied to 600V ultrahigh voltage, is stable in performance, low in viscosity, high in conductivity and beneficial to volume production, and can reduce the production cost.