The invention provides a corrosion method of a shell inner wall of total-tantalum capacitor. The method includes: using NaOH and deionized water to prepare a NaOH solution; cleaning a tantalum shell with deionized water, drying in a drying oven, taking out and naturally cooling; adding the NaOH aqueous solution into the dried and cooled tantalum shell; drying the tantalum shell loaded with the NaOH aqueous solution in the drying oven, and then naturally cooling; removing the residual NaOH aqueous solution in the tantalum shell; cleaning the tantalum shell after the NaOH aqueous solution is removed with deionized water, and drying in the drying oven. The corrosion method has the advantages that the roughness of the shell inner wall is increased while the quality of the tantalum shell is unaffected, the specific surface area of the inner wall is increased, decomposed ruthenium oxide during the thermal decomposition of ruthenium trichloride can be well combined with the inner wall of the tantalum shell, the adhesive force of the ruthenium oxide is increased, and the specific surface area and capacity of a cathode are increased at the same time.