Objective This study aimed to explore the composition and diversity of microbial flora in different liquid milk samples. Methods High-throughput sequencing technology was used to sequence the V3-V4 region of bacterial 16S rRNA in liquid milk, and the bacterial community structure of four groups of liquid milk samples at the phylum and genus levels was studied. Results There were 119 Operational Taxonomic Units (OTUs) in the four groups of samples,and the unique OTUs accounted for 15.0%,6.85%,8.86%,and 12.35%,respectively. At the phylum level,Firmicutes and Proteobacteria were the common phyla of the four groups of liquid milk. The relative abundances of Firmicutes in the four groups of samples were 38.9%, 73.8%,20.9%,and 29.6%,respectively. The relative abundances of Proteobacteria were 46.9%, 10.0%, 28.0%, and 17.2%,respectively. At the genus level, the dominant bacterial genera of Sample 1 were Bacillus and Brevunmdimonas, the dominant bacterial genus of Sample 2 was Bacillus, the dominant bacterial genera of Sample 3 were Cloacibacterium and Stenotrophnomonas, and the dominant bacterial genera of Sample 4 were Bacillus, Microbacterium and Deinococcus. Conclusion It can be seen from the phylum level that the composition of bacteria in the four groups of samples was basically similar. Meanwhile, at the genus level, Acinetobacter,Bacillus and Klebsiella contained in liquid milk belong to psychrophilic bacteria, which can cause spoilage and deterioration of liquid milk. This research provides an important basis for exploring the prevention and control measures of spoilage bacteria in liquid milk in the future.