The invention relates to a non-circular rib for concrete. A square rib, a rectangular rib, an oval rib, a trapezoid rib, a triangular rib and a corner-smoothed rib are arranged on the principle section of the non-circular rib for the concrete. The ribs in various shapes of square, rectangle, oval, trapezoid, triangle and smoothed-corner take the place of the traditional circular rib, so that the rib is easy to strap, the occupied space is saved, the distance from the resultant force of the tensile force of the rib to the boundary of the concrete becomes nearer or a concrete protection layer is thicker, the adhesion force between the rib and the concrete is increased due to the change of the shapes, and guarantee is provided for the safety of a building. The non-circular rib comprises a smooth rib and the ribbed ribs with non-circular principle sections.