A method for manufacturing a seamless wheel rim includes the steps of deeply drawing a pre-cut circular aluminum alloy plate into a cup-shaped embryo body, punching out the bottom surface thereof to form a hollow cylinder, then putting it into an expanding-pressing female die with an expanding die cavity at both ends thereof respectively, and finally pressing and expanding both ends of the embryo body by two sets of expanding-pressing male dies to form a seamless aluminum wheel rim in sequence.