The poor compatibility between drilling fluid additives and cementing slurry can lead to downhole accidents and inferior cementing quality. Therefore, this paper intends to study on the influence of sulfomethyl phenol formaldehyde resin (SMP) on cement slurry. This paper studies the influence of SMP on the rheological property, thickening time, aggregate stability of cement slurry, and compressive strength of cement stone, and studies the influence of SMP on the concentration of metal ions of cement slurry. And this paper analyzes the influence of SMP on the microstructure of cement slurry via vacuum freeze-dry technology of liquefied nitrogen combined with environmental scanning electron microscope. Finally draw the conclusions: SMP and metal ions with high valence (Fe3+, etc.) set off complexation reaction in cement slurry, which increases the molecular weight of complex compound adsorbed on the surface of the cement particles. Meanwhile, Zeta potential is decreased after SMP is added to cement slurry, and the cement slurry becomes thickened as the particles move from agglomeration and diffusion equilibrium towards aggregation direction. After SMP and metal ions with high valence (Fe3+, horizontal ellipsis etc.) set off the complexation reaction in cement slurry, a dense "film" is formed on the surface of the particles to prevent cement particles from contacting free water, which will reduce the hydration rate of cement particles, increase the thickening time of cement slurry, and reduce the compressive strength of the cement stone to only two-fifth of the compressive strength of cement stone with original formula.