The utility model relates to an inversed S type runner for a mixed-flow turbine, which comprises a runner crown, a runner band and a plurality of curved surface blades connected between the runner crown and the runner band. The water inlet side of the blades is in an inversed S type, and thus, the flow state of the inlet of the blades during low flow capacity and high flow capacity is improved; simultaneously, the head of the water inlet side is kept small and the highest optimum efficiency is achieved;the blades are lengthened, the wider running range with high efficiency is achieved; and i.e. an electric station always has high-efficiency performance indexes during the running work conditions, such as low flow capacity, high flow capacity and optimum work conditions. The shape of the molded line of the runner crown of the blades, and the shape of the molded line of the runner band of the special blades are slightly in an inversed S type; the inlet flow rate is reduced, the flow state in the runner is improved and the running stability of a machine group is enhanced.