The invention provides a corrosion technique for improving the strength of a corrosion layer of middle-high pressure corrosion foil. The corrosion technique for improving the strength of the corrosion layer of middle-high pressure corrosion foil comprises the steps that after plain foil is treated through a NaOH aqueous solution with the concentration being 0.1-10N, 0.02-2 wt% of polymeric additives are added into a corrosive solution with the concentration being 2.0-15N for the electrochemical reaction, then treatment is conducted with a chemical corrosive solution with the concentration being 0.1-10 N, then treatment is conducted with an HNO3 aqueous solution with the concentration being 0.1-10 N, and drying is conducted after cleaning. By adoption of the technique, the strength of the corrosion layer of the middle-high pressure corrosion foil is improved, and thus the bending strength of produced middle-high pressure polarized formed foil is guaranteed.