Abstract: To address the corrosion issue of methanol fuel on engine fuel system metals and promote its application, 8 typical corrosion inhibitors were selected for the research focused on H62 brass, T2 copper, 45# carbon steel, and HT200 cast iron in a methanol system containing 0.50% water and 0.50% formic acid by mass fraction. Corrosion weight loss tests （336 h at 38 ℃±1 ℃） and surface morphology characterization were conducted to screen effective inhibitors and explore their synergistic effects in blends. Results revealed that at a total inhibitor concentration of 1.00% by mass, benzotriazole, phytic acid, and cyclohexane individually exhibited remarkable comprehensive corrosion inhibition for all four metals, with benzotriazole showing the most outstanding performance. Blend studies demonstrated that the equimolar mixture of 0.50% benzotriazole and 0.50% phytic acid by mass significantly outperformed both the individual components （1.00% by mass） and the ternary mixture （0.33% benzotriazole+0.33% phytic acid+0.33% cyclohexane by mass） in protecting all metals. The physical adsorption of cyclohexane molecules on metal surfaces interferes with the formation of the benzotriazole−phytic acid composite chemical film in the ternary system, thereby reducing corrosion inhibition efficiency.