An electrolytic solution includes an organic solvent, an electrolyte, and an additive. The additive includes a first compound represented by Formula 1, where R1 is selected from one of a single bond, substituted or unsubstituted alkoxy, C1-C6 alkylene, and C2-C6 alkenyl; R2 and R3 each are independently selected from one of substituted or unsubstituted alkoxy, C1-C6 alkylene, and C2-C6 alkenyl; and R4 is B or P. Since the first compound includes an N-containing group that may be combined with a protonic acid in the electrolytic solution, the electrolytic solution have good stability; moreover, the cycle performance of a lithium secondary battery is improved.