The present invention relates to electrolyte of a high-voltage lithium-ion battery, comprising a non-aqueous organic solvent, lithium salt and an electrolyte additive; the electrolyte additive comprises the following ingredients based on the total weight of the electrolyte: 1%-10% of fluoroethylene carbonate, 1%-5% of dinitrile compound and 0.1%-2% of 2-methyl maleic anhydride; further, the electrolyte can be further added with additives such as 0.2%-2% of lithium bisoxalatoborate and 1,3-propane sultone. The present invention also relates to a high-voltage lithium-ion battery using the electrolyte, with the charging cut-off voltage being greater than 4.2V and smaller than or equal to 4.5V. The electrolyte of the high-voltage lithium-ion battery provided by the present invention can protect the positive electrode and also form good SEI at the negative electrode, and the high-voltage lithium-ion battery has good cycle performance and storage performance.