The invention relates to a fast hydrolyzable slow releasing polycarboxylate superplasticizer and a preparation method thereof. Under the protection of nitrogen or inert gas, with participation of a water-soluble initiator and a chain transfer agent, polymerization reaction among a double bond polyether monomer, a double bond carboxylic acid monomer and a water-soluble mico-crosslinking function auxiliary is carried out in an aqueous solution; the pH of the reaction system is adjusted to 7-8 with alkali to obtain the fast hydrolyzable slow releasing polycarboxylate superplasticizer. The fast hydrolyzable slow releasing polycarboxylate superplasticizer can perform delaying dispersion on concrete in half to one hour, and introducing the fast hydrolyzable slow releasing polycarboxylate superplasticizer in compound can make up the blanking period of dispersion effect due to property difference between a water reduction-type water reducing agent and a slump resistant water reducer, so that risks of separation and slump loss of concrete can be greatly reduced.