The invention discloses a minimum wetted perimeter volute section numerical value solving method based on a speed moment conservation principle. When all section of a volute are solved through the speed moment conservation principle, the target of reducing the wetted perimeter, namely the friction area, of the sections is persisted, and thus the hydraulic efficiency of the volute can be easily improved. Two symmetrical straight lines are still used on the lower portions of the sections of the volute on the axis face to form an axis face stream line without a turn, compared with a traditional trapezoid section, the difference that a circular arc in tangent to the two straight lines replaces the structure of two transition circular arcs exists, and the perimeter of the volute is obviously reduced than that of the traditional structure. By means of the two-straight-line type waist at the lower portion of the section mode, water flow entering the volute from an impeller can be prevented from disengaging, the arch formed by the upper single circular arc reduces the section wetted perimeter, and the friction loss of the water flow along the pass is reduced. The numerical value solving method and process for calculating and acquiring all geometric dimensions of the novel section are provided, meanwhile, the stress distribution in the volute becomes more even through the structure, and a possibility is provided for reducing the wall thickness of the volute.