In order to develop a biomass-based superplasticizer, kraft lignin (KL) was grafted with isopentenol polyoxyethylene ether (TPEG) to prepare a novel macromonomer (KL-TPEG). It was shown that the retention ratio of the aliphatic CC bond increased from 81.07% to 90.20% with the increase of m(TPEG)/m(KL). When the grafting ratio was increased, the average number of TPEG grafted on one KL molecule was approximately 1.4, 3.1, 4.6, 6.2 and 7.6. The star-like structure was also confirmed by FT-IR, 1H NMR and GPC. KL-TPEG had favorable surface activity and dispersion stability on the cement particles. It was illustrated that the shear stress and shear viscosity of the cement slurries with KL-TPEG were significantly less than that of blank slurry. The dispersion-retention ability of KL-TPEG on the slurry was also gradually enhanced with the increase of the grafting ratio of TPEG. It was seldom reported on the biomass-based TPEG. Through modified with KL, the rheology behavior and the dispersion-retention ability of TPEG was greatly improved, and the cost of TPEG was also reduced, thus this study not only promoted the development of biomass-based macromonomer, but also helped for the high value utilization of lignin.