A commutate silencer of a computer system is described. The commutate silencer of the computer system is installed at the back end of the computer system, and comprises a shield device, a commutate device and at least one partition. The shield device comprises a first shield and a second shield, in which the first shield comprises an opening, the first shield and the second shield construct a first cavity, and the first cavity includes a plurality of outlets. The commutate device comprises a frame and a plurality of commutate diversion plates, in which the frame construct a second cavity, the diversion plates traverse the second cavity, the second cavity has an inlet and a ventilated opening, and the ventilated opening is connected to the opening of the first shield. The at least one partition is located in the first cavity and the second cavity, so as to separate the inlet, the ventilated opening and the outlets into a plurality of sub-inlets, a plurality of sub-ventilated openings and a plurality of sub-outlets, respectively.