The present invention relates to a thermosetting electrolyte composition for a lithium secondary battery and a lithium secondary battery including the same, and particularly, to a thermosetting electrolyte composition for a lithium secondary battery, which includes LiPF6 as a first lithium salt, a non-aqueous organic solvent, and a polymer or oligomer containing a unit represented by Formula 1, wherein the polymer or oligomer containing the unit represented by Formula 1 is included in an amount of 0.6 wt % to 15 wt % based on a total weight of the thermosetting electrolyte composition for a lithium secondary battery, and a lithium secondary battery including the same.