The invention provides a right-angled elbow provided with flow guiding rib plates and belongs to the technical field of fluid engineering. The central arc of the elbow is a circular arc. All sections perpendicular to the central arc are all round sections. The diameter of each round section is equal to the diameter of an inlet and the diameter of an outlet of the elbow. The diameter of the inlet and the outlet of the elbow is D. The flow guiding rib plates are symmetrically distributed on the two sides of the inner wall of the elbow. The thickness of each flow guiding rib plate is 0.005D, and the width of each flow guiding rib plate is 0.07D. The molded line of each flow guiding rib plate and the center line of the elbow are located in the same camber. The distance between one end of each flow guiding rib plate and the inlet of the elbow and the distance between the other end of each flow guiding rib plate and the outlet of the elbow are both 0-0.15D. The end of a water inlet of each flow guiding rib plate is cylindrical. The right-angled elbow provided with the flow guiding rib plates is scientific and simple in structure and reasonable in design, restrains secondary backflow, reduces the resistance loss caused by the secondary backflow by 4%-8% and improves the hydraulic efficiency of the whole pipeline or the whole mechanical equipment system.