The noise of gasoline generator sets has a wide-band frequency spectrum characteristic, and the muffler equipment is required to be able to withstand high air velocity and high temperature and pressure, and not afraid of water and humidity. When the temperature rises, the performance of the muffler changes little. In some cases, micro-perforated plate composite mufflers are often used in treatment. A micro-perforated plate muffler with a double-layered structure with a hole diameter of 0.5 to 1 mm and a perforation rate of 1% to 3% is processed from a thin steel plate of 0.5 to 1mm, which has a good absorption effect on medium and high frequency noise. In multiple layers, the thickness of the cavity depends on the absorption band. At low frequencies of 125 to 250 Hz, the thickness of the cavity is 150 to 220 mm. At intermediate frequencies of 500 to 1000 Hz, the cavity is 80 to 120 mm. When the high frequency is 2000 ～ 4000Hz, the cavity is 30 ～ 50mm. In order to prevent the sound wave from propagating along the length of the tube in the cavity of the micro-perforated plate, a muffler that requires a higher amount of sound will be added every 0.5m long . The cross-section of the double-layer micro-perforated plate and tube muffler is circular.