Abstract. Polyester fiber was attempted to reduce the noise in large-scale equipment. Sound absorbing performance of the polyester fiber with different parameter was investigated based on the standing wave method. Experimental result showed that the sound absorbing coefficients were ameliorated along with the increases of thickness of the polyester fiber. Meanwhile, for the same thickness, the corresponding sound absorbing coefficient of polyester fiber with density of 0.3g/cm 3 was better that of 0.2 g/cm 3 . Furthermore, it could be observed that sound absorbing coefficients were almost increasing linearly along with increase of frequency when thickness of the polyester fiber was low. It would be found that there existed peak of the sound absorbing coefficients when the thickness was large. Especially when the thickness reached 24mm, the sound absorbing coefficients in the frequency range of 2000Hz ~ 6000Hz exceeded 90%. The excellent sound absorbing performances of the polyester fiber would be propitious to reduce noise in large-scale equipment.