A kind of P(PEGMA-r-AA)-b-PMMA slow-release polycarboxylate superplasticizer nano-particles was synthesized by aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA), using 4-cyano-4-(thiobenzoylthio) pentanoic acid (CPADB) as chain transfer agent and 4,4′- azobis ( 4-cyanovaleric acid ) ( ACVA ) as initiator. By comparison with conventional polycarboxylate superplasticizers, the role of its unique microsphere structure in regulating cement hydration and improving concrete performance was systematically revealed. The successful synthesis of the polymer was confirmed by ¹H-NMR, IR and GPC. The results of TEM show that the diameter of polycarboxylate superplasticizer nano-particles increases gradually from (12.5±1.3)nm to (31.8±2.5)nm with the growth of the hydrophobic PMMA block. The XPS analysis further indicate a corresponding increase in its adsorption layer thickness on the surface of cement particles. Performance studies demonstrate that the retarding effect of this superplasticizer becomes weakened as the particle size increases, and it can effectively reduce the volume of harmful pores (20 ~ 200 nm) in cement paste. Moreover, while maintaining excellent slump retention, the material also contributes to a certain improvement in the compressive strength of concrete.