Four kinds of imidazoline inhibitors with different hydrophobic group i.e. 2-heptadecyl-aminoethylimidazoline （IM-17）, 2-undecyl-aminoethyl-imidazoline （IM-11）, 2-nonyl-aminoethyl-imidazoline （IM-9）, 2- butyl-aminoethyl-imidazoline （IM-4） had been synthesized and characterized by IR and UV spectra. The inhibition performance of these imidazoline inhibitors for CO2 corrosion of N80 in 3% NaCl solution was investigated through linear polarization resistance, polarization curve and electrochemical impedance spectroscopy under static and flow conditions. The results showed that the inhibition efficiency under static condition decreased in the order of IM-9〉IM-4〉IM-11〉 IM-17, i.e. the inhibition efficiency was related with both the solubility and the length of carbon chain of hydrophobic group of imidazolines. In contrast, the inhibition efficiency at 5 m/s decreased in the order of IM-9〉IM-1〉IM-17〉IM-4, and solution flow （5 m/s） dramatically worsened the inhibition performance of imidazolines.