A negative-pressure packaging method for aluminum electrolytic capacitors including: penetratedly arranging a capacitor element in a seal; placing the capacitor element, the seal and a case at an inner chamber of an accommodating mechanism; sealing the accommodating mechanism; vacuumizing the accommodating mechanism to allow the inner chamber to be in a negative pressure state; subjecting the seal and the case to packaging, such that the seal is located at a first depth of the case; and subjecting the seal and the case to pressing, such that the seal is located at a second depth of the case, where the second depth is closer to a bottom of the case with respect to the first depth. The defect in the prior art that the sliding distance of the seal on the inner wall of the case is too long is overcome, reducing the generation of friction heat, and preventing the melting of the seal. Therefore, the packaging method provided herein can ensure a reliable air tight seal between the seal and the case, improving the product stability and service life.