The invention relates to a method for corroding the low-impedance anode aluminum foil for electrolytic capacitor and the chemical pretreatment solutions. The method comprises the following steps: the first step of primary electrolytic corrosion, the second step of chemical treatment and the third step of secondary electrolytic corrosion; the chemical pretreatment solutions consist of 4.0N to 5.0N of hydrochlorides, 0.15N to 5.0N of sulfates, 0.05N to 0.15N of phosphoric acids, 0.01N to 0.05N of nitric acids and 1.0N to 2.0N of aluminium chlorides. The invention forms the uniformly distributed pits with larger clearances and passive films enduring the corrosion on the surface of the clean aluminium foil and then implements the expanding treatment, so the impendance of the obtained etching foil is outstandingly lowered and in particular the invention has outstanding effects on the electrode foil with a voltage ranging from 50 to 100V. The use of the method controls the size, distribution and clearance of the pits to a certain extent, improves the corrosion morphology and increases the clearance of the pits and distribution uniformity so as to lower the impedance of the anode foil. The invention is suitable for the corrosion of the low-voltage aluminium foil with a voltage ranging from 25V to 100V, can lower the impedance of the anode foil by a great amount and can be used for preparing the low-impedance electrolytic capacitor anode aluminium foil.