The invention relates to a reducing valve in the agriculture water-saving irrigation field and discloses an irrigation multifunctional mass-flow reducing valve. The irrigation multifunctional mass-flow reducing valve comprises a valve body, a support plate, a valve rod, a valve core, a valve cap, a base, an opening-closing valve body, a spring positioning piece, a bolt and a spring. In the working state, when the upstream pressure is instable, under the actions of spring force and water pressure, the valve rod and the valve core can move up and down in the axial direction to regulate the current cross section, then different head losses of localities are caused, and the function of stabilizing the downstream pressure is achieved. According to the irrigation multifunctional mass-flow reducing valve, a throttling port is perpendicular to the water flowing direction, and the pass flow is large; the lowest end of the valve body is provided with the opening-closing valve body, through the adjustment of the opening-closing valve body, the valve core can be closely attached to the wall face of the lower side of the throttling port, and the function of closing the valve is achieved. The irrigation multifunctional mass-flow reducing valve has the advantages that the pass flow is large, the adjusting range is wide, the pressure adjusting effect is good, the assembly is convenient, and the irrigation uniformity can be greatly improved if the irrigation multifunctional mass-flow reducing valve is applied to the agriculture irrigation system; meanwhile, the delicate design of the opening-closing valve body can omit an opening-closing valve body in a pipeline, and the investment is reduced.