Method for preparing polycarboxylate superplasticizer by combination of polyether macromonomers of two structures

The invention discloses a method for preparing polycarboxylate superplasticizer by the combination of polyether macromonomers of two structures. The method is characterized by comprising the steps that a macromonomer A (methyl allyl polyoxyethylene ether), a macromonomer C (methyl-2-buten-1-ol polyoxyethylene ether) and water are added into a reactor and are stirred, mixed and dissolved at 40-60 DEG C, then small monomers (acrylic acid and the like) are added, mercaptoacetic acid is added, the temperature is increased to be 75-85 DEG C, an ammonium persulfate solution is added dropwise within 70-90min, heat preservation is carried out for 2-3 hours at the 75-85 DEG C to perform polymerization reaction, then materials after reaction are cooled to be at the room temperature, and the materials are neutralized through a sodium hydroxide aqueous solution of the mass percent concentration being 30% until the pH value ranges from 6.8 to 7.2 so as to prepare the polycarboxylate superplasticizer. The macromonomers and the like are combined and copolymerized, the polycarboxylate superplasticizer with high performance is compounded, and balance and performance regulation between slushing and slump retaining of existing polycarboxylate superplasticizer products are facilitated.