The invention provides a preparing method of a superhigh-strength aluminum alloy cylinder, and belongs to the technical field of precise plastic forming. The method comprises the steps of mold preparing, blank turning, annealing, and appearance machining and is characterized in that after annealing and before appearance machining, jar extrusion, multi-pass thinning drawing, and closing in are carried out in sequence, and after appearance machining, heat treatment is carried out. A large-draw-ratio variable wall thickness thin-wall closing-in cylinder is adopted, the problems that superhigh-strength aluminum alloy is poor in moulding, tensile deformation appears, cracking is prone to appearing, in the cylinder manufacturing process, concave pits easily appear in the closing-in position andthe conical neck part, the surface is rough and has grains, and is even cracked, the thickness and the size is not controllable, and the production stability is poor are solved, and the product yieldand the yield of the method are both above 98%.