Disclosed is a 700V high-voltage aluminum electrolytic capacitor electrolyte. The electrolyte comprises 50-80% of main solvent, 20-50% of auxiliary solvent, 5-20% of main solute, 2-10% of auxiliary solute, 0.1-1% of auxiliary additive and 5-15% of spark additive, wherein the main solute comprises one or more of azelaic acid, ammonium hydrogen azelate, ammonium sebacate, decane dicarboxylic acid, 7, 9-dimethyl-7, 9-dimethoxy carbonyl-1, 11-dodecane dicarboxylic acid, and 7, 8-dimethyl-7, 8-dimethoxy carbonyl-1, 14 tetradecane dicarboxylic acid; and the auxiliary solvent comprises one or more of ammonium salicylate, salicylic acid, oxalic acid, malonic acid, succinic acid, ammonium benzoate, ammonium maleate, ammonium hydrogen maleate, ammonium adipate and hexanedioic acid. The spark voltage of the electrolyte is greater than 700V; and in addition, the electrolyte is simple to prepare, stable in performance and excellent in related parameters.