In order to investigate the effects of different ester monomers on the dispersion performance and dispersion retention performance of slow-release polycarboxylate superplasticizer and their action mechanism, different slow-release polycarboxylate superplasticizers were prepared with different molecular structure ester monomers as modified raw materials. The macroscopic dispersion performance and dispersion retention performance, and the microscopic structural change and action mechanism were analyzed by the tests of fluidity of cement paste with time, Zeta potential, total organic carbon, electrical conductivity, Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The results show that the dispersion retention performance of slow-release polycarboxylate superplasticizer modified with monoester monomer (hydroxyethyl acrylate, hydroxypropyl acrylate and methyl acrylate) and diester monomer (dimethyl maleate) as functional monomers are superior while the fluidity at 4 h is still improved comparing to the initial fluidity. At the same time, compared with the unmodified control group, the later dispersion performance is better, while the fluidity at 4 h is significantly improved. The main mechanism is as follows: the ester group is slowly hydrolyzed in the alkaline environment of cement paste and produces the anchoring group carboxyl group to achieve the effect of dispersion. The steric hindrance effect and the electronegativity of the contained groups with different molecular structures lead to different hydrolysis rates and degrees of hydrolysis, resulting in different dispersion performance and dispersion retention performance of various slow-release polycarboxylate superplasticizer.