Objective Explore the effects of sodium chloride and tryptone in the components of mannitol salt agar on the quality of mannitol salt agar, and investigate the product quality of 5 domestic brands and 1 imported brand of mannitol salt agar sold on the market. Methods After preparing mannitol salt agar with different brands and concentrations of sodium chloride and tryptone, the effects of sodium chloride and tryptone on the quality of mannitol salt agar were investigated using plate coating counting and semi quantitative scoring method. Quantitative determination of the growth of different types of Staphylococcus aureus and Escherichia coli on 5 domestic brands and 1 imported brand of mannitol salt agar. Refer to GB 4789.28-2013 to compare the growth rate, growth index, and colony size of different brands of culture media for different strains, and evaluate the quality of each brand of culture media. Results There are significant differences in the growth rate and growth index of experimental strains on mannitol salt agar prepared with different types and concentrations of sodium chloride or tryptone. The growth index of non target bacteria in different brands of mannitol salt agar is qualified, but there are significant differences in the growth rate and colony size of the target bacteria. Conclusion Sodium chloride and tryptone have a significant impact on the quality of mannitol salt agar, which directly determines whether the medium is qualified. There are significant differences in the quality of different brands of mannitol salt agar sold domestically and internationally, and the quality of domestic mannitol salt agar is better than that of imported medium.