With the experimental facility and measurement system of dielectric barrier discharge（DBD）

this paper studied the characteristic of plasma assisted combustion（PAC） actuator discharge under different thickness dielectric layers

applied voltage and air gap distance.On the basis of the experimental data

the parameters such as the terminal voltages and the discharge current on the air gap clearance are calculated according to an equivalent circuit.The results show that

the thickness of medium strongly influences discharge pulse times;with the increasing of applied voltage

discharge pulse times increases

and discharge starting time continuously brings forward;while with the decreasing of air gap distance

actuator discharge intensity distinctly enhances

and the discharge is more uniformity.