<p>Since magnesium (Mg) is promising in the practical application of degradable oral barrier membranes, it is crucial to gain a comprehensive understanding of the degradation mechanisms in the oral environment. Artificial saliva is commonly used to simulate the oral environment <i>in vitro</i>, but it lacks organic components which have significant effects on the Mg degradation. Proteins are the key organic constituents in the oral cavity and their levels are fluctuant. Hence, varying concentrations of bovine serum albumin (BSA) were added into artificial saliva to investigate their effects and mechanisms on the corrosion behavior of Mg by corrosion tests and multiple computational simulations. Electrochemical and 15-day long-term immersion tests indicate that increasing the BSA concentration promotes the formation of calcium-phosphate products on the Mg surface, thereby reducing the corrosion rate of Mg. The density functional theory and molecular dynamics analyses demonstrate that the BSA can promote the formation of the Ca–P products through radial distribution function and mean square displacement analysis and increase the binding energy of the Ca–P species with the Mg substrate. In summary, this study offers a comprehensive understanding of how different contents of protein in artificial saliva affects the corrosion behavior of Mg, which is essential for promoting the application of Mg as oral barrier membranes.</p>