Water reducer is an anionic surfactant. It is adsorbed on the surface of cement particles to make the particles display electrical properties. The particles repel each other because they carry the same charge, so that the cement particles are dispersed and the excess water between the particles is released to produce a water-reducing effect. On the other hand, since the water reducing agent is added, an absorption film is formed on the surface of the cement particles, which affects the hydration rate of the cement, makes the growth of cement crystals more perfect, reduces the capillary gap where moisture evaporates, and improves the hardness and structural compactness of the cement mortar.