A hard-disk pulling device includes two separating plates, a cover member, a hook portion and a linkage mechanism. A receiving space is defined between the separating plates for receiving a hard disk unit. The cover member is pivotally connected to one of the separating plates to selectively cover the receiving space. The linkage mechanism includes a first linking rod pivotally connected to the cover member, and a second linking rod pivotally connected to the first linking rod and the separating plate. The hook portion is connected to one end of the linkage mechanism facing away from the cover member for directly abutting against the hard disk unit. When the cover member is rotated to pull the hook portion through the linkage mechanism, the hook portion pushes the hard disk unit out of the receiving space.