The invention discloses a viscosity reduction type polycarboxylate superplasticizer used for high -strength concrete. The polycarboxylate superplasticizer is prepared from, by weight, 20.0-40.0 parts of water reduction type PCE mother liquor, 2.5-5.0 parts of viscosity reduction type PCE mother liquor, 2.5-15.0 parts of slump retaining type PCE mother liquor, 0.02-0.05 part of air entraining agent, 0.02-0.05 part of antifoaming agent, 0.5-0.8 part of thickening time control agent, 0.01-0.02 part of corrosion inhibitor, 0.01-0.02 part of antiseptic and proper amount of water. According to the viscosity reduction type polycarboxylate superplasticizer, three kinds of mother liquor of the water reduction type PCE, the viscosity reduction type PCE and the slump retaining type PCE are adopted, proper evacuation time required by the high-strength concrete can be obtained by adjusting the ratio of the three kinds of mother liquor according to practical conditions of raw materials such as binding material and aggregate, and viscosity of the high-strength concrete is controlled.