The invention discloses a polycarboxylate superplasticizer for pervious concrete and a preparation method thereof. The weight-average molecular weight of the polycarboxylate superplasticizer is 50000-100000. The polycarboxylate superplasticizer is prepared from the following raw materials in parts by weight: 180-220 parts by weight of isopentenyl polyoxyethylene ether, 15-20 parts by weight of an unsaturated monomer, 2.0-6.0 parts by weight of an early strength functional monomer, 1.0-4.0 parts by weight of an initiating agent, 1.0-3.0 parts by weight of a slurry maintaining agent, 1.0-3.0 parts by weight of a chain transfer agent, 190-210 parts by weight of deionized water and an appropriate amount of sodium hydroxide solution. The polycarboxylate superplasticizer for pervious concrete has the beneficial effects that the polycarboxylate superplasticizer is low in mixing amount and high in water reducing rate and has good early strength; the working performance of the pervious concrete can be substantially improved; and the compressive strength and water permeability of the pervious concrete are remarkably improved.