The paper aims to study the inhibitive action of DCSLE on carbon steel in sulfuric acid medium. DCSLE were obtained by soaking and ultrasonic method with water as solvent and its main functions were characterized by FTIR. The inhibition effect of DCSLE on carbon steel corrosion in 0.5 mol/L H2SO4 solution was studied by weight loss method, potentiodynamic curves and electrochemical impedance spectroscopic (EIS) at 25~40 ℃ and the corresponding corrosion mechanism was discussed. The results showed that DCSLE had a good inhibition effect on carbon steel in 0.5 mol/L H2SO4 solution. Its inhibition efficiency increased with increase of concentration, and decreased with the increase of (40 ℃< 25 ℃< 30 ℃< 35 ℃). The inhibition performance reached to 92.85% with 0.6 g/L at 35 ℃. The electrochemical test showed that DCSLE was a mixed inhibitor which mainly inhibited the cathode reaction. The inhibition mechanism of DCSLE was that DCSLE was adsorbed on the surface of carbon steel by a mixture of physical and chemical adsorptions, forming a protective film to prevent the corrosion of acid solution, and the adsorption followed the Langmuir adsorption isotherm model. SEM showed that the corrosion of carbon steel was obviously controlled by adding DCSLE. The DCSLE can effectively inhibit the corrosion of carbon steel in 0.5 mol/L H2SO4 solution. It is a natural green corrosion inhibitor with wide application prospects.