The invention relates to a water outlet edge of a runner blade of a radial-axial flow turbine. The blade comprises a blade body, a stress dropping triangular block at the upper tip and a stress dropping triangular block at the bottom ring. Additional triangular blocks are arranged on the blade and close to the upper tip and the bottom ring. The sizes of the stress dropping triangular block at the upper tip and the stress dropping triangular block at the bottom ring are determined, wherein the spatial distance between the P1 and the P2 is D1/40-D1/20 and not smaller than 75mm, and the D1 is the normal diameter of the inlet of a radial-axial runner. The water outlet edge has the advantages that stress among the outlet of the blade and the upper tip and the bottom ring thereof can be reduced, the flow around energy of the outlet can be reduced effectively, and cracking of the blade and vibration of the outlet Karman vortex are avoided. In addition, the rigidity of the water outlet of the blade is enhanced, deformation in numerical-control machining and transport process is decreased, weldability of the water outlet of the blade is improved and the rigidity of the triangular region can be improved after the process of welding.