The invention discloses a preparation method of an anti-clay and shrinkage-reducing type polycarboxylate superplasticizer. Phytic acid, unsaturated alcohol ether, a polymerization inhibitor and a catalyst are added to a reaction vessel, uniformly stirred, heated to 80-200 DEG C and subjected to an esterification reaction for 1-12 h, a product I obtained after the reaction is cooled to room temperature, and a snowflake-like anti-clay macromonomer is obtained; the snowflake-like anti-clay macromonomer and solvent water are added to the reaction vessel, then a polyether macromonomer, unsaturatedcarboxylic acid, an unsaturated derivative and an initiator are added to the reaction vessel, uniformly stirred, heated to 50-100 DEG C and subjected to a reaction for 1-12 h, a product II obtained after the reaction is cooled to room temperature, alkali is added to regulate pH to 6.5-7.5, and the polycarboxylate superplasticizer is obtained. The polycarboxylate superplasticizer has excellent anti-clay, water-reducing and shrinkage-reducing effects and good dispersity, thereby having good application prospect and market competitiveness in the field of water reducers. The preparation method further has the advantages that the synthesis process is simple, safe, environmentally friendly, non-toxic, harmless, clean and pollution-free, industrial production is realized easily, and the method has good social benefits and economic benefits.