Emission treatment system and control method

An emission treatment system for a vehicle is provided that includes a plasma reactor is disposed in a main exhaust pipe and configured to reduce noxious emissions of an engine. A bypass pipe is connected to the main exhaust pipe both before and after the plasma reactor such that exhaust emissions can be caused to bypass the plasma reactor. A control valve is disposed at a position where the main exhaust pipe and the bypass pipe intersect, and is configured to selectively open and close the main exhaust pipe and the bypass pipe. A power supply unit supplies power to the plasma reactor and the control unit is coupled to the power supply unit and the control valve controlling a voltage of power supplied to the plasma reactor and an operation of the control valve.