The utility model discloses an air expansion drum comprising a hollow drum core component and a fastening component, wherein the hollow drum core component comprises a rubber pipe, a hollow drum core, a three-hole end cover and a four-hole end cover; the rubber pipe is arranged outside the hollow drum core, and the rubber pipe is parallel to two ends of the hollow drum; the three-hole end cover and the four-hole end cover are fixed on threaded holes of the hollow drum core through screws; one hole of the four-hole end cover is provided with an air nozzle; the fastening component comprises a main clamping cover and an auxiliary clamping cover; the auxiliary clamping cover is fixed on the hollow drum core, and the position of a hollow hole in the auxiliary clamping cover corresponds to the position of the air nozzle on the hollow drum core; and the main clamping cover is fixed opposite to the auxiliary clamping cover through a screw. The air expansion drum has the advantages of guaranteeing that the hollow drum core and the rubber pipe do not make displacement as the hollow drum core is positioned in the middle of the rubber pipe, and are combined together with the mode of a concave-convex groove arranged on the surface, and guaranteeing that the air expansion drum does not leak air after inflated as two ends of the drum core are closely fixed by the three-hole end cover and the four-hole end cover which have conicity.