Abstract: With the aggravation of environmental pollution, the development and application of recycled polyester fibers based on bottle chip is of great significance. In this paper, recycled polyester hollow fibers and skin core type heat-bonded fibers were used as raw materials to prepare sound absorbing materials with multi-scale micropores by hot air consolidation. The structure and properties of polyester hollow fibers were characterized. Standing wave tube method was used to study the relationship between linear density and sound absorbing effect of hollow fibers, and a "multistage" sound absorbing theory was proposed. The results show that the hollow fibers with the linear density of 10 D has the largest hollowness, the best toughness and the best sound absorption effect. The sound absorption coefficient and noise reduction coefficient increase linearly with the increase of thickness. When the thickness is 2 cm, the noise reduction coefficient (NRC) is greater than 0.5, which is expected to become an ideal sound absorption material.