In addition to the mechanization and automation of production, the technological progress of aluminum electrolytic capacitors is mainly composed of two processes: corrosion phase activation. The corrosion coefficient of aluminum foil is very high (100 for low voltage capacitor foil and 25 for high voltage), and the aluminum foil with different hole morphology can be corroded according to the performance requirement of capacitor. Corrosion process is a kind of dynamic balance process of corrosion solution type, concentration, temperature, composition, structure, surface state, foil speed, power source type, w***eform, frequency, voltage and so on. The question is how to get the best dynamic balance and how to determine the most tran***issible equilibrium according to the requirement. Therefore, the corrosion process can not be said to h***e reached the best state. The existing enabling process has been able to produce high-quality dielectric oxide films, and different dielectric oxide films can be made according to different requirements, for example, for DC capacitors, γ and γ '-type crystalline alumina films can be made. For AC capacitors, they are amorphous films. The greatest development of the technology is that the aluminum hydroxide film can be transformed into the dielectric alumina film and the waterproof layer can be formed on the surface of the aluminum hydroxide film. In addition, it can eliminate the defects and cracks of the dielectric film.