Using vacuum and pressure impregnation methods, this method is conducive to the electrolyte completely soaking the electrolyte paper and penetrating into the fine corrosion pit of the anode foil, thereby reducing the probability of capacitance reduction and loss value increase caused by the electrolytic paper not being fully soaked. The key points of the impregnation process are the need to control the level of the impregnation, the impregnation time and the type of electrolyte.