Objective To investigate the culture effect of MRS AGAR medium of 5 domestic brands and 2 imported brands on lactic acid bacteria, and to compare the product quality. Methods Using spiral coating counting method, the growth of 3 strains of lactobacillus specified in GB 4789.28—2013 and 9 strains of non-national standard Lactobacillus (including standard strains and laboratory isolated strains) on the different MRS AGAR medium were quantitatively determined. By comparing the growth rate of different brands of medium to different strains, the quality of each brand of medium was evaluated. Results There were significant differences in the growth rate of GB 4789.28 standard strain on different brands of MRS AGAR media, and some of the medium had quality problems. Streptococcus thermophilus ST-21 isolated from probiotics powder had good growth ability in reference medium, and there were significant differences in growth rate among different brands of MRS AGAR medium. Conclusion The result of this study indicated that there are great differences in the quality of MRS AGAR media of different brands at home and abroad; Streptococcus thermophilus S-T21 can effectively evaluate the quality difference of different brands of media, and is suitable for the quality control of MRS AGAR media.