Abstract: In order to isolate marine bacteria with broad-spectrum bacterial inhibition from the rhizosphere soil of mangrove plants, the experiment was conducted with four common pathogenic bacteria as indicator bacteria, E. coli, Staphylococcus aureus, Salmonella and Streptococcus. Bacteria were isolated from the rhizosphere soil of mangrove plants using M10 and P3 media, and the isolates were screened for antibacterial activity by solid agar punching method; genomic DNA of the isolates was extracted; 16S rDNA gene was amplified by PCR and sequenced, while a phylogenetic tree was constructed by using the neighbor-joining method. The results showed that 654 strains of bacteria were isolated from the soil of mangrove plants, among which 107 strains had antibacterial activity, accounting for 16.4% of the isolated strains. Strain M36 had the strongest antibacterial activity against E. coli and Streptococcus, with a circle diameter of 13 mm and 16 mm, respectively; strains P19 and P25 had the strongest antibacterial activity against S. aureus, with a circle diameter of 16 mm; strain P83 had the strongest antibacterial activity against Salmonella, with a circle diameter of 13 mm; strains M36 and P31 had the broadest antibacterial spectrum. The strains with antibacterial activity were classified into four genera, namely Enterobacter, Bacillus, Staphylococcus, and Burkholderia, based on the results of the two media, among which Enterobacter was the dominant genus, followed by Bacillus, accounting for 69.2% and 15.9%, respectively. The results suggested that there were bacteria with broad-spectrum antibacterial activity in the rhizosphere soil of mangrove plants.