The invention relates to a hydraulic design method of a radial guide blade of a
diagonal flow pump. The method gives design formulas of main geometric parameters of the guide blade; and the main geometric parameters include a base circle
diameter D3 of the guide blade of the
diagonal flow pump, an inlet width (axial width) b3 of the guide blade, an inlet shaft surface speed vm3 of the guide blade, an exclusion coefficient
omega 3, an inlet
peripheral composite velocity vu3 of the guide blade, an inlet blade width coefficient KDBY of the guide blade, an inlet blade width b3' of the guide blade, a
front cover plate round angle
radius RDBY of the guide blade, a
front cover plate round angle
radius coefficient KTSY of the guide blade, a back cover plate round angle
radius RTSY of the guide blade, an inlet liquid flowing
angle alpha 3' of the guide blade, an inlet placing
angle alpha 3 of the guide blade, a blade thickness
delta 3 of the guide blade, a
throat coefficient a 3 of the guide blade, a blade number z of the guide blade, a
throat speed v3, a dispersion section outlet speed v4, an outlet
diameter D4 of the guide blade, a dispersion angle phi, a dispersion section inlet area F3, a dispersion section outlet area F4 and the like. The method is different from a hydraulic design method of a radial guide blade of a common pump, improves the flowing conditions, and achieves the purposes of improving diversion and energy conversion.