The invention discloses a plasma gas waste gas treatment device. The plasma gas waste gas treatment device comprises a gas inlet pipe and a plasma decomposition cavity. The gas inlet pipe is arranged on the upper portion of the side wall of the plasma decomposition cavity and used for feeding waste gas to be treated. The anode electrode and the cathode electrode of a plasma power source are arranged on the top of the plasma decomposition cavity. The plasma decomposition cavity is internally provided with a columnar shell electrode panel parallel to the axis of plasma gas formed between the anode electrode and the cathode electrode of the plasma power source. Anode conductive liquid is arranged between the columnar shell electrode panel and the side wall of the plasma decomposition cavity. The anode conductive liquid makes contact with the columnar shell electrode panel, and the liquid level is lower than the horizontal plane where the gas inlet pipe is located. The columnar shell electrode panel is used for forming the plasma gas with the cathode electrode of the plasma power source so that the waste to be treated can be treated. According to the plasma gas waste gas treatment device, due to the fact that plasma flame extends to the columnar shell electrode panel, the waste gas treatment efficiency is improved.