This kit is suitable for extracting 1-5 mL of bacterial solution. It adopts a unique silica matrix membrane adsorption technology and reagent formulation, and efficiently and specifically binds plasmid DNA in solution by centrifugal adsorption columns under high salt condition, each adsorption column can adsorb up to 30 μg of plasmid DNA, and maximally removes proteins, genomes, RNAs, and other impurities.