The inhibition effect of brainea insignis extract (BIE) on the corrosion of Q235 steel in HCl solution was investigated by means of mass loss measurement, polarization curve measurement and electrochemical impedance spectroscopy. The results showed that BIE could effectively inhibit the carbon steel corrosion in HCl solution, as the BIE concentration was up to 560 mg·L^-1, the corrosion rate of Q235 steel decreased to 1.125 g·m^-2·h^-1, namely the corrosion inhibition efficiency reached 94.3%. Electrochemical analysis shows that the BIE extract suppressed mainly the cathodic corrosion reaction. With the increasing concentration of BIE extract, the charge transfer process on the metal surface was hindered increasingly, resulting in enhanced corrosion inhibition performance. The highest corrosion inhibition efficiencies calculated from the fitting of polarization curves and electrochemical impedance spectroscopy were 95.8% and 95.3%, respectively, which were in agreement with the result of mass loss measurement. The adsorption action of BIE molecules on the steel surface followed Langmuir, Temkin adsorption isotherms and the EI-Awady thermodynamic-kinetic model, and belonged to heterogeneous adsorption, whilst there should exist lateral interaction forces between the adsorbed organic molecules. Spectral analysis and surface morphology observations confirmed the existance of the adsorption action and corrosion inhibition of the extract molecules, respectively.