The invention discloses a synthesis method of a polycarboxylic acid high-performance water 
reducing agent of a star-like structure, belonging to the field of a water 
reducing agent. According to the synthesis method, polybasic 
alcohol, (methyl) 
acrylic acid, a 
polyethylene glycol compound and the like are used as esterification raw materials, and the polycarboxylic acid high-performance water 
reducing agent of the star-like structure is prepared through a sequential esterification and 
polymerization method, i.e., the (methyl) 
acrylic acid and the polybasic 
alcohol are used as reactants, a star-like polymerizable active end is prepared through 
esterification reaction under the action of a catalyst, and then the polycarboxylic acid high-performance water reducing agent is prepared from the star-like polymerizable active end and esterification 
macromolecule, a molecular weight 
regulator and an unsaturated 
carboxylic acid monomer under the action of an initiator through free 
radical polymerization reaction. The synthesis method has the advantages of simplicity, easiness in control, high 
polymerization degree, low cost, no 
pollution, capability of realizing the polycarboxylic acid high-performance water reducing agent of the star-like structure connected with a plurality of polycarboxylic acid molecules, and more superior 
cement paste fluidity and holding capacity, good 
cement adaptability and concrete application performance compared with the conventional linear and comb-shaped polycarboxylic 
acid water reducing agent in the case of normal and low added amount.