| Noise pollution, one of the three major pollution, has became a global problem. Nowdays people pay more and more attention on the environment, sound-absorbing materials are playing an increasing important role, their application is growing rapidly and higher requirements have been put forward on the acoustic properties of the materials as well. The development of non-woven sound-absorbing materials, which have better sound absorption properties, can replace wooden materials, inorganic fiber materials currently in use. Besides, non-wovens have light weight and better ornamentality, can be conveniently installed and most of them can be recycled to reuse. Therefore, the study on non-woven sound-absorbing materials has great significance.In this paper, firstly, the requirements of the fibers of the nonwoven sound absorbing materials were studied based on the requirement of the acoustic properties, fiber processability, environmental requirements and raw material costs, and polyester fibers were chosen. Secondly, the process technology of non-woven materials, such as opening, blending, carding, lapping and needle punching process were discussed. Finally, the sound absorption and sound insulation properties of PET composite needle punching absorbing materials were studied. The influences of the thickness, basis density and the fiber fineness on the sound absorption properites of the composite mateirals were investigated. The influences of the after-needle-punching, after-thermal-molding process and hot air process on the propertries of the PET composite needle punching absorbing materials were studied. In addition, sound-absorbing materials also exhibit other properties when used in a specific application, so the basic properties (thickness, basis density and porosity), penetrating ability (permeability, pore size size), heat-insulating property and mechanical tensile properties of PET non-woven sound-absorbing materials are analyzed as well.Based on the above study, the conclusions can be summarized as follows:(1) Polyester fiber has good basic properties, and can meet sound absorption performance requirements. It's recyclable, environmentally friendly and can be thermally processed. After trial experiments, the process parameters were selected as: needled density 4000 needles / m, frequency 1200 thorn / min, output drawing of fiber web i 1:1.5, needled depth of 7～11 mm, the pros and cons of needling of 2~8.(2) PET needle punching materials have good air permeability with the porosity of more than 90%. Thermal insulation properties of specimens are proportional to thickness, surface density, and are inversely proportional to porosity, permeability, etc. Through the analysis of mechanical properties of the specimens, the relationship between the fracture strength and bulk density was characterized in a linear equation.(3) The acoustic absorption / acoustic insulation performance of non-wovens were testd by using the SW463 of materials testing instrument, it were found that thickness has a greater impact on the acoustic properties. Increasing thickness can improve the sound absorption performance, but doesn't obviously affect on the sound insulation. Increasing the basis density can both improve the sound absorption performance and sound insulation performance. To a certain extent, the finer fiber fineness, the better sound absorption, and doesn't effect obviously on the sound insulation. Using 5cm thick cavity can both significantly improve the acoustic properties of materials, and also save interior space.(4) The optimum conditions of secondary reinforcement of the PET composite needle punching sound absorbing materials are as follows: after-thermal-molding temperature 150℃, after-thermal-molding time 4min～5min, after-thermal-molding pressure 7MPa～12MPa. After thermal molding, the materials have higher hardness, better dimension stability, higher breaking strength and less MD / CD ratio. In addition, the sound absorption coefficient of the materials becomes smaller because of the lower thickness.
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