For large-scale production of plasma-activated water (PAW) with high concentrations of reactive species, a novel high-power dielectric barrier (DBD) PAW generator with superior antibacterial properties has been developed. The discharge power of this generator is 970 W. The concentrations of long-lived species H₂O₂, NO₂⁻, and NO₃⁻ in the PAW treated by plasma for 6 min were 59.27, 718.49, and 3341.42 μmol/L, respectively. The pH decreased from 7.70 to 3.05, and the energy cost for the total active species generation decreased from 40.62 to 33.88 MJ/mol. As the plasma exposure time increased, the bactericidal ability of PAW was substantially enhanced with the increase in acidification of PAW and the increase in active species concentration. With the increase of standing time of the suspension after mixing PAW and bacterial solution, the internal reactions of PAW are fully processed, resulting in the inactivation of more bacteria and the enhancement of the bactericidal effect. As the contact area between the suspension and the air became larger, the NO₂⁻ in PAW were oxidized to NO₃⁻, which affected the generation of ONOO⁻ and other key active species, resulting in a great attenuation of the activity of PAW and a decrease in the bactericidal ability. Finally, the PAW treated with plasma for 6 min and mixed with the bacterial solution in a closed centrifuge tube for 20 min can achieve a more desirable bactericidal effect, and the bactericidal rate reached 99.99%.