The work aims to develop a new plant extract inhibitor, and study its corrosion inhibition effect and mechanism on carbon steel in 1 mol/LHCl solution. The extract ofLycium barbarum leaves (LBLE) was prepared by ultrasonic-assisted extraction method, and the structure was characterized by infrared spectroscopy (FTIR). The corrosion inhibition effect on carbon steel was evaluated by weight loss method and electrochemical method, and the surface morphology of carbon steel was analyzed by scanning electron microscopy (SEM). The hydrophobicity of carbon steel surface was analyzed by the contact angle tester, and the thermodynamics and dynamics were analyzed. Finally, the corrosion inhibition mechanism was discussed. LBLE had a good adaptability to temperature. When the concentration of LBLE was 800 mg/L, the corrosion inhibition efficiency was above 90% in the temperature range of 30-60 ℃. When the concentration of LBLE was only 100 mg/L in the temperature range of 30 ℃-40 ℃, the corrosion inhibition efficiency of carbon steel could reach 91.91% and 90.71% respectively, indicating that LBLE in 1 mol/L HCl solution had good corrosion inhibition properties. Compared with the corrosion current density and corrosion potential without corrosion inhibitor, the polarization curve showed that the corrosion current density of both cathode and anode decreased with the addition of LBLE, and the corrosion potential shifted positively and did not exceed 85 mV, which indicated that LEBE was a mixed corrosion inhibitor mainly based on anode. The AC impedance showed that the charge transfer resistance increased with the increase of LBLE concentration, and the adsorption layer formed by LBLE inhibitor molecules between the electrode surface and the solution played a significant protective role, effectively blocking the charge transfer between the electrode surface and the solution. The adsorption thermodynamics showed that the Gibbs free energy was ?30 kJ/mol in the temperature range of 30-60 ℃, indicating that the adsorption process of LBLE on the surface of carbon steel was a mixed adsorption process of chemical adsorption and physical adsorption. The adsorption kinetics showed that the activation energy of the corrosion reaction increased when LBLE inhibitor was added, and the corrosion reaction was more difficult to occur. LBLE is an efficient and environmentally friendly corrosion inhibitor for pickling. On the one hand, the chemical components such as flavonoids and phenolic acids with —OH and —OR structures in LBLE are easy to protonate, and the protonated components are adsorbed on the surface of carbon steel by physical action due to electrostatic interaction. On the other hand, the main component molecules of LBLE contain a large number of heteroatoms such as O and N and unsaturated groups such as double bonds and aromatic rings, which interact with Fe atoms through the empty orbital of heteroatoms or π electrons to produce chemical adsorption at the interface of hydrochloric acid solution/carbon steel. The protective film formed by the physical and chemical adsorption between LBLE and carbon steel surface effectively inhibits the charge transfer at the interface between hydrochloric acid solution and carbon steel, showing excellent corrosion inhibition effect, which provides a theoretical basis for industrial application.