In order to solve the problem of bag expanding of braised brisket with potato, the microorganism of expanding bag was separated, purified, identified and gas production characteristics were studied. Seven dominant strains were obtained. Morphology observation, 16S rRNA sequence and MALDI-TOF MS were combined to identify the obtained strains. As a consequence, strain 001 and 002 were identified as Bacillus subtilis, strain 003 and 004 were Staphylococcus epidermidis, strain 005 and 006 were Bacillus licheniformis, strain 007 were the member from Bacillus coagulans. When those strains were innoculated into the braised brisket with potato, obvious gas generation was observed for strain 001, 002, 005, and 006 which was the main reason for the bag expansion of braised brisket with potato.