Abstract: Self-assembled inhibition films were prepared by 2-(3-carboxyl) phenyl iminomethyane phenoxy acetic acid Schiff base (K2L2) on carbon steel surface, and the inhibition performance for carbon steel in the environment of the actual work was studied by polarization curve, electrochemical impedance spectroscopy and scanning electron microscopy (SEM). The results indicated that the oil water salinity, temperature, pH value, flow velocity and H2S concentration had infulences on the inhibition perpormance of self-assembled films of K2L2 in saturation CO2 oilfield water, but there was still a higher inhibition efficiency, and the inhibition efficiency of self-assembled films of K2L2 still reached 80.0% with 200 mg/L H2S in oilfield water.