A foldable duster can be folded to enable selective use of a single-sided or double-sided pile as well as a change in length of the duster. The duster includes a stationary member whose two ends form a pivotally connecting portion and a fastening portion respectively. The fastening portion is configured for connecting with a handle. The pivotally connecting portion is pivotally connected with a folding member. A dusting sleeve coated with pile threads is mounted around the stationary member and the folding member. The folding member can be swung to a position where the folding member and the stationary member form a straight line, thereby straightening the dusting sleeve and extending the duster to its full length. When the folding member is swung to overlap the stationary member, the dusting sleeve becomes folded, and the duster is shortened. Thus, the foldable duster provides convenience of use.