Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the corrosion mechanism of lightweight tinplate in protein beverage. It is found that proteins in beverages can decomposed into hydrogen sulfide (H2S) and then hydrolyzed to H+ and S2-. Hydrogen evolution reaction between H+ and carbon steel could produce a large amount of H2, the gas assembled at the interface result in the exfoliation of corrosion product layer and accelerate the tinplate’s corrosion ultimately. S2- is oxidized in the medium and generated a small fraction of S which lead to the sulfur blackening phenomenon in beverage cans.