Provided are a lithium secondary battery including a cathode, an anode, a separator, and a gel polymer electrolyte, wherein the gel polymer electrolyte includes an acrylate-based polymer and a charge voltage of the battery is in a range of 4.3 V to 5.0 V, and a method of preparing the lithium secondary battery. A high-voltage lithium secondary battery of the present invention has excellent capacity characteristics at a high voltage of 4.3 V or more.