Abstract: The present application discloses a polyhydroxy aromatic intermediate, preparation thereof and use thereof in a polycondensate water-reducer with branched side chains. The polycondensate water-reducer with branched side chains has a branched side chain structure which provides a stronger steric hindrance. The synergistic effect of the branched side chains and the rigid skeleton of the aromatic ring greatly improves the water-reducing ability. Especially under a condition of low water/cement ratio, the improvement in water-reducing ability is more obvious. The branched polyether side chain is more conducive to the formation of a thicker water film layer, which has an obvious viscosity reduction effect. The conformation of the branched polyether side chain is less affected by different ionic environments in the pore solution in cement, and thus has a stronger adaptability to various raw materials.