The invention discloses a method of raising the high-temperature internal pressure forming yield of an aluminum alloy barrel. The method is used for carrying out treatment on the aluminum alloy barrelof which the welding is completed and in which a longitudinal seam is formed. The method comprises the following steps that one, mounting is carried out, concretely, the aluminum alloy barrel is arranged on a bending press and the longitudinal seam is located on the stress center plane of the aluminum alloy barrel; and two, preforming is carried out, concretely, preforming operation is carried out on the aluminum alloy barrel by using the bending press, a pressing block is placed in a position of a section of part to be subjected to partial moulding deformation, and pressure is applied to thealuminum alloy barrel through the pressing block, wherein in the press-bending process, the position of the pressing block is adjusted gradually along the part to be subjected to the partial mouldingdeformation till the deformation of whole section of part to be subjected to the partial moulding deformation is completed. During press-bending pre-deformation, the seam is subjected to relatively low-degree plastic deformation, thus the crack of the seam is prevented effectively. After the method is applied to the preforming on the aluminum alloy barrel, the high-temperature internal pressure forming first-pass yield of subsequent pneumatic structure parts reaches 100%.