The invention relates to the technical field of concrete admixtures, in particular to a clay-resisting slow-release slump-retaining type polycarboxylate superplasticizer and a preparation method thereof. With polyether macromonomers, unsaturated carboxylic acid, unsaturated carboxylic ester, dibasic acid anhydride, a crosslinking agent, amide monomers, unsaturated phosphate ester, phosphate, an oxidizing agent , a reducing agent, a chain transfer agent, a neutralizing agent and water as raw materials, the clay-resisting slow-release slump-retaining type polycarboxylate superplasticizer is synthesized at normal temperature. Ester groups, amide groups and phosphate ester are introduced into the molecular structure of the polycarboxylate superplasticizer, and light crosslinking of the polycarboxylate superplasticizer is realized through the long-chain ester crosslinking agent, so that the superplasticizer has a good clay-resisting and slump-retaining effect and has the advantages of low mixing amount, high water reducing rate, high adaptability to clay-containing sand, good slump retaining performance and the like; besides, only normal-temperature polymerization is needed, the processis simple, the production cost is low, and the superplasticizer is suitable for industrial production.