The polycarboxylate superplasticizers (PCE) were synthesized by one- time feeding and aqueous solution free radical copolymerization with isopentenyl polyoxyethylene ether (TPEG) as macromonomer, acrylic acid (AA) as small monomer, ammonium persulfate (APS) as initiator, and sodium methacrylate sulfonate (MAS) as chain transfer agent. By desiging different acid- ether ratios for changing the initial concentration, the influence of AA concentration on the polymerization rate of PCE was investigated, further fitted the reaction order of AA. The results show that with the progress of the PCE reaction, the concentration of AA decreases and the conversion rate of AA increases.With the initial concentration of AA increaseing from 0.2376 mol/L to 0.9008 mol/L, the polymerization rate increases from 1.3 × 10^-4 mol/(L ? s) to 4.8 × 10^-4 mol/(L ? s), the polymerization rate is increased with the increasing concentration of AA, and the kinetic experiment shows that the reation order of AA is 0.9554.