The paper proposes a low ripple high voltage converter applied in plasma field. The structure of the circuit combines conventional symmetric voltage multiplier and a parallel resonant circuit. High-output-voltage low-output-voltage-ripple converter can be achieved by the way of superposition and cancellation of capacitors' alternating signal from the parallel resonant circuit. The problem of high output voltage ripple created in conventional voltage multiplier can be improved. Comparing to conventional interleaved circuits for decreasing output voltage ripple and three-phase parallel-type circuits, the structure of the proposed converter needs less components. Operating modes and output-voltage-ripple analysis were developed. For implement of the circuit, the parameters of the components are provided in the paper. Finally, a prototype converter with input voltage 400 Vdc, output voltage 20 kVdc, output voltage ripple 0.95% and output power 400 W is implemented in the laboratory to verify the feasibility of the proposed method.