A foldable textile holder for a flat mop includes a rectangular main board provided to be pivotally connected to a handle of the flat mop and two wing plates respectively and pivotally to two opposite ends of the main board relative to a major axis of the main board by two pivot elements. The main board and the two wing plates are situated on a same plane when cleaning the floor and form a U-shape after the two wing plates being folded, wherein each pivot element temporarily positions a corresponding one of the two wing plates when the two wing plates are upwardly folded or the main board and the two wing plates are situated on a same plane.