Lignin-modified polyoxyethylene ether monomer (KL-TPEG) was prepared from lignin and unsaturated polyoxyethylene ether. A series of lignin-based polycarboxylic acid water reducers PCE-Ls with different lignin content were prepared from KL-TPEG. The structure of PCE-Ls was characterized, and the properties of PCE-Ls and PCE-B were tested by dispersibility, rheology and compressive strength of concrete. The results showed that PCE-Ls had good surface activity and air entraining properties, and the 5min foam height was >50mm, much higher than that of PCE-B 20mm. The surface tension is only 36.01 mN/m when the mass concentration is 50 g/L. Compared with the traditional Polycarboxylic Water Reducer PCE-B, the dispersion of PCE-Ls is not much different, but the initial fluidity of PCE-Ls is higher than 300 mm; the slump of PCE-Ls dispersed concrete is more than 110 mm, which has better and easier performance. The fitting model shows that PCE-Ls dispersed cement paste has lower yield stress, better stability and lower plastic viscosity.