A method for electrolytic solution injection of a secondary battery, the secondary battery comprising a positive electrode plate, a negative electrode plate, a separator and an 5electrolytic solution, wherein, a positive electrode active material of the positive electrode plate comprises a high-nickel ternary positive electrode material, and the electrolytic solution comprises a solvent, an electrolyte salt and a film-forming additive, wherein the electrolytic solution is composed of an electrolytic solution S1 and an 10electrolytic solution S2, the method comprising: as a first injection, injecting the electrolytic solution S1 in the secondary battery, wherein a film-forming additive in the electrolytic solution S1 is a negative electrode film-forming additive for forming a solid electrolyte interphase film configured to isolate a material of the negative electrode from the electrolytic solution; performing sealing and formation; and as a second injection, injecting the electrolytic solution S2 in the secondary battery, wherein a film-forming additive in the electrolytic solution S2 is a positive electrode film-forming additive for forming a fine cathode electrolyte interphase film configured to inactivate surface active sites of the high-nickel ternary positive electrode material, wherein the negative electrode film-forming additive is selected from vinylene carbonate, ethylene sulfate, 4-methyl-2,2-dioxo-1,3,2-dioxathiolane, trifluoroethyl phosphate, lithium 2-trifluoromethyl sulfonamide, or lithium bisfluorosulfonimide; and wherein the positive film-forming additive is selected from dimethyl sulfite, and diethyl sulfite, or acrylonitrile. a positive electrode active material of the positive electrode plate comprises a high-nickel ternary positive electrode material, and the electrolytic solution comprises a solvent, an electrolyte salt and a film-forming additive, wherein the electrolytic solution is composed of an electrolytic solution S1 and an 10electrolytic solution S2, the method comprising: as a first injection, injecting the electrolytic solution S1 in the secondary battery, wherein a film-forming additive in the electrolytic solution S1 is a negative electrode film-forming additive for forming a solid electrolyte interphase film configured to isolate a material of the negative electrode from the electrolytic solution; performing sealing and formation; and as a second injection, injecting the electrolytic solution S2 in the secondary battery, wherein a film-forming additive in the electrolytic solution S2 is a positive electrode film-forming additive for forming a fine cathode electrolyte interphase film configured to inactivate surface active sites of the high-nickel ternary positive electrode material, wherein the negative electrode film-forming additive is selected from vinylene carbonate, ethylene sulfate, 4-methyl-2,2-dioxo-1,3,2-dioxathiolane, trifluoroethyl phosphate, lithium 2-trifluoromethyl sulfonamide, or lithium bisfluorosulfonimide; and wherein the positive film-forming additive is selected from dimethyl sulfite, and diethyl sulfite, or acrylonitrile. as a first injection, injecting the electrolytic solution S1 in the secondary battery, wherein a film-forming additive in the electrolytic solution S1 is a negative electrode film-forming additive for forming a solid electrolyte interphase film configured to isolate a material of the negative electrode from the electrolytic solution; performing sealing and formation; and as a second injection, injecting the electrolytic solution S2 in the secondary battery, wherein a film-forming additive in the electrolytic solution S2 is a positive electrode film-forming additive for forming a fine cathode electrolyte interphase film configured to inactivate surface active sites of the high-nickel ternary positive electrode material, wherein the negative electrode film-forming additive is selected from vinylene carbonate, ethylene sulfate, 4-methyl-2,2-dioxo-1,3,2-dioxathiolane, trifluoroethyl phosphate, lithium 2-trifluoromethyl sulfonamide, or lithium bisfluorosulfonimide; and wherein the positive film-forming additive is selected from dimethyl sulfite, and diethyl sulfite, or acrylonitrile.