In this work, it has been shown that a mixture SDS/CnDMAA can be used as the switchable surfactants. A COMPASS forcefield is one of the successful options in this study. Molecular simulation has the potential to predict inter- and intra-molecular interactions. The results showed that CnDMAA can significantly affect the interfacial behavior of SDS surfactant in an oil/water system after N2 injection, which is mainly related to the electrostatic interaction. Increasing the nonpolar tail of CnDMAA changed the configuration of the SDS/CnDMAA mixture at the oil/water interface