In this work, a floating-electrode dielectric barrier discharge plasma device was constructed based on the principle of dielectric barrier discharge, and its application of bacterial inactivation was studied. The experimental results show that the device has a significant sterilization performance in the inactivation of Staphylococcus aureus and Escherichia coli. The inactivation efficiency of Staphylococcus aureus and Escherichia coli is more than 99.99% within 30 s. Treatment gap distance also plays an important role in sterilization and the best distance is 1 mm.