The Castor Leaf Extract (CLE) was prepared using pure water as the solvent and was obtained through the decoction method. CLE exhibits outstanding anti-corrosion nature as an inhibitor in H2SO4 media for X70 pipeline steel. The electrochemical test has shown that the inhibition efficiency of CLE can be up to 92.8 %. CLE, a mixed-type corrosion inhibitor, is capable of inhibiting both cathodic and anodic processes in the X70 pipeline steel/H2SO4 system. The morphology of the X70 steel surface turns into significantly flatter and brighter with increasing CLE. The adsorption of CLE at the X70 steel/H2SO4 interface follows the Langmuir monolayer adsorption model, which encompasses both physical and chemical adsorption processes. Theoretical calculations demonstrate that CLE is able to effectively protect X70 steel from corrosion by H2SO4 solution.