The invention belongs to the technical field of lithium-sulfur batteries, and particularly discloses a lithium-sulfur battery electrolyte. The electrolyte contains an additive with a double-= NOR cyclic conjugate structure. By adding the additive of the structure into the electrolyte, the polarization effect in the charging and discharging process of the lithium-sulfur battery is reduced, the conversion efficiency of polysulfide is improved, the deposition of insoluble sulfide is reduced, and finally, the capacity and the cycle stability of the lithium-sulfur battery are obviously improved.