Due to the stronger adsorption of polycarboxylate ether (PCE) superplasticizers to clay than cement particles, PCE fails to adjust the workability of cement paste containing clay. In this study, hexadecyl trimethyl ammonium bromide (CTAB) was used as an efficient clay-specific sacrificial agent to make PCE more compatible in cement paste containing Montmorillonite (Mt, one kind of clay). The experimental results indicated that CTAB can obviously improve the fluidity of cement paste containing Mt, with the increasing of spread diameter in the mini slump test. CTAB as a macromolecular compound with positive charge was able to interact with Mt by electrostatic adsorption, which was effective to hinder the hydration and swelling of Mt and therefore broke the absorption of Mt to PCE. In conclusion, CTAB has great potential to resolve the incompatibility of PCE to cement paste containing clay and contributes to the corresponding enhanced workability.