The invention discloses a concrete viscosifying type viscosity modifier and a preparation method thereof. The preparation method comprises the following steps: dissolving a modified polyether monomer,an unsaturated amide monomer, an unsaturated carboxylic acid monomer and a cross-linking agent into deionized water to obtain a mixed monomer solution; dissolving the unsaturated amide monomer and the unsaturated carboxylic acid monomer into the deionized water, and recording as a solution A; slowly dropping an initiator solution and the solution A into the mixed monomer solution under the conditions of N2 and 40-60 DEG C, continuously stirring and reacting at a temperature of 60-90 DEG C, regulating the pH value, adding water and diluting, thereby obtaining the viscosity modifier. The viscosity modifier disclosed by the invention is excellent in compatibility with a polycarboxylate superplasticizer, is capable of effectively regulating the concrete cohesion and solving the problems suchas concrete disintegration and bleeding without influencing the slump retaining property and setting time of the concrete, and is favorable for development of compressive strength of the concrete. Meanwhile, due to optimal regulation of the polymerization process, the stability of the product is improved, the dosage sensitivity of the product is reduced, and the operability of on-site constructionis improved.