The clay minerals attached to aggregate have serious deterioration effects on the workability of cement-based materials, which restricts the dispersion function of polycarboxylate superplasticizer. In this paper, the influence of polyaluminum chloride on the adsorption of polycarboxylate superplasticizer about clay was studied by Zeta potential, absorbance, and X-ray diffraction methods. And then, the improvement effect of polyaluminum chloride on the workability of mortar and concrete with calcium-based bentonite was studied, and the interaction mechanism was explored. The results show that polyaluminium chloride reduces the surface adsorption of calcium-based bentonite to polycarboxylate molecule, but it cannot inhibit the intercalation adsorption. The 6% (mass fraction) polyaluminum chloride improves the workability of mortar and concrete mixed with calcium-based bentonite. This behavior partly improves the clay resistance of polycarboxylate superplasticizer, providing a new strategy for solving the use of aggregate with high clay in practical engineering.