The invention discloses a graphene ultralow-temperature power lithium battery. The power lithium battery comprises a battery case, a negative electrode insulation sheet, a battery cell, a positive electrode insulation sheet and a cap. The battery cell comprises a positive electrode plate, a negative electrode plate and a diaphragm. The positive electrode plate comprises a positive electrode current collector, and positive electrode material coatings arranged on two side surfaces of the positive electrode current collector respectively; each positive electrode material coating is prepared by coating the surface of the positive electrode current collector with a positive electrode material mixture; and the positive electrode material mixture contains a nanoparticle positive electrode material, a positive electrode binder, a positive electrode mixed conductive agent and a positive electrode solvent, wherein the nanoparticle positive electrode material is a lithium iron phosphate nanoparticle, and the positive electrode mixed conductive agent contains, by weight, 97-99 parts of a positive electrode conductive agent base material, 0.2-0.4 parts of graphene, 0.2-0.4 parts of SP and 0.2-0.4 parts of KS-6.