We developed an atmospheric-pressure plasma equivalent circuit consisting of partial-discharge calibration and a power equivalent circuit. Then we proposed a matching circuit design method to increase power transfer efficiency between the power supply and the planar dielectric plasma device. Past studies have proposed that adding matching circuits between the power supply and the plasma effectively increases plasma power absorption. However, they did not consider partial discharge under atmospheric pressure or ripple and harmonic effects on absorption in their power supply simulations. Thus, we used a plasma equivalent circuit that could simulate partial discharge and a power supply equivalent circuit that could simulate the electrical properties of the actual power supply so as to analyze and calculate plasma power transfer efficiencies of three matching circuits. The results showed that when the matching capacitor was made parallel to the plasma load, argon and helium plasma power transfer efficiencies increased.