Herein, we report a rational design and synthesis of a highly-efficient and eco-friendly glucomannanderivative (GA-2) by the introduction of the thiazole and Schiff base groups into glucomannan (GA). After confirmation of GA-2 by the spectroscopic methods, it was introduced as corrosion inhibitor withexcellent anti-corrosion action for mild steel (MS) in the simulated seawater. As-obtained results revealthat GA-2 has a significantly enhanced anticorrosion performance, and its inhibitive efficiency reaches98.8% at the 0.5 mmol L1 inhibitor concentration, much higher than that of GA (69.8%) and the intermediatederivative GA-1 (81.2%). The significantly enhanced protection performance could be attributed tothe rich S heteroatoms, aromatic rings, and Schiff base groups in the GA-2, which strongly promotes thechemisorption as well as physisorption between GAD and MS. X-ray photoelectron spectroscopy (XPS)results, show that the appearance of N-Fe and S-Fe bonds confirms the strongly anchoring interactionbetween GA and MS. Furthermore, according to the quantum chemical calculations, the results fromthe lowe energy gap and radical distribution function (RDF) analyses further confirm the strongchemisorption of GA-2 at the surface of steel, which illustrates the excellent inhibition performance atthe molecule and atom level.