System for handling cardboard reels to feed machines that produce cardboard tubes, comprising a station (P) for picking up the superimposed cardboard reels (1), a reel unwinding station (1) comprising at least one unwinding unit (UU) capable of supporting the reels to be unwound, in the unwinding station (U) being also provided splicing means configured to splice a tail portion (TY) of a reel (1 Y) being exhausted with a new reel (1W), and handling means (D) for moving the reels (1) along a predetermined path between the reel pick-up station (P) and the unwinding station (U). Said at least one unwinding unit (UU) comprises several supports (403; 404) mounted on a vertical axis carousel structure (G).