Two novel cationic Gemini surfactants (2C n GeQS, n = 12, 18) was designed and prepared via amidation and quaternization reaction. The molecular structure of the 2C n GeQS was confirmed by FTIR, 1H NMR and elemental analysis. The critical micelle concentration (CMC) of aqueous solutions of these surfactants was determined by surface tension measurements, and the surface activity parameter, such as effectiveness (π CMC), efficiency (pC 20), critical micelle concentration (CMC), maximum surface excess (Г max), minimum surface area (A min), were obtained. The results showed that 2C n GeQS have a higher surface activity than conventional monomeric surfactant. The CMC decreases with an increment in hydrophobic chain length, however, the surface tension at the cmc (γ CMC) shows the opposite trend. The thermodynamic parameters indicate that both micellization and adsorption processes of 2C n GeQS were spontaneous. In addition, the results obtained from weight loss measurements show that 2C n GeQS exhibits a greater protective effect than that of DTAB; inhibition efficiency (ηw%) of 2C12GeQS, 2C18GeQS%, and DTAB is 95.6%, 96.86%, and 52.8% for A3 carbon steel at 1 × 10−3 M.