The invention discloses an adjustable variable-differential-pressure constant-flow blanking plug, and belongs to a blanking plug of a water distributor of oil field water injection equipment. The blanking plug is composed of a salvaging fixing device, a water nozzle sleeve and a water inlet filtering cap. Through the technical characteristics, the blanking plug achieves the advantages that the adjustable variable-differential-pressure constant-flow blanking plug can automatically adjust the area of the cross section of a water nozzle according to changes of water injection pressure so as to control flow, and therefore the water injection rate is kept constant under the condition that the water injection pressure fluctuates, and water injection requirements are guaranteed; the shape of an outer water nozzle is similar to an isosceles triangle, the two equal sides of the triangle of the outer water nozzle are in outward circular arc transition and in the shape of a parabola, when front pressure and rear pressure of an inner water nozzle fluctuate within a certain range, the inner water nozzle and the outer water nozzle can automatically adapt to changes of difference between the front pressure and the rear pressure of the inner water nozzle and make corresponding adjustment, and therefore the influences of the changes of the differential pressure on the flow can be effectively reduced, injection allocation amount can be kept constant basically, and quantitative water injection of oil fields is achieved.