This invention provides a method for processing perfluorocompounds exhaust, that employs thermal energy produced by the reactions occurred in a plasma reactor to convert liquid water into steam. The steam is then directly introduced into the plasma reactor to participate in the reactions of plasma stream. This invention resolves the high temperature problem encountered by the reaction chamber during combustion. In addition, this invention is provided with a combustion chamber connecting to the reacting chamber. Air is introduced into the combustion chamber to combust with hydrogen so as to remove a great mount of hydrogen produced by the combustion of the perfluorocompounds exhaust.