A water reducing agent is a concrete admixture that reduces the amount of water used for mixing while maintaining the slump of the concrete. Most of them belong to anionic surfactants, such as lignosulfonate and naphthalenesulfonate oxymethylene polymers. After adding the concrete mixture, it has a dispersion effect on the cement particles, which can improve the workability, reduce the unit water consumption, improve the fluidity of the concrete mixture, or reduce the amount of cement per unit and save cement.