Abstract: With the charge－voltage figure many key parameters may be obtained for studies on the applications of dielectric barrier discharge (DBD)plasma, such as the discharge energy, gap capacitance, dielectric capacitance, cut－in voltage, gap voltage, and discharge gap electric field. At the same time the stability of DBD plasma can be diagnosed by the charge－voltage figure which changes with changes in the operation conditions. The underlying principles, experimental simulation results and actual application developments are des－cribed.