PU foams are widely used in the automobile industry not only for their lightweight properties, but also as sound-absorbing and seat cushioning materials. The effects of particles on the sound absorption properties of PU composite foams were investigated. PU foams containing 3 wt% melamine particles showed excellent sound absorption properties. However, when the particle content exceeded 3 wt%, particle agglomeration occurred, leading to reduced sound absorption. A dispersant was added during the fabrication process to improve the interfacial compatibility between the PU matrix and melamine particles, resulting in a well-developed cavity and pore structure. The sound absorption characteristics of the PU composite foams were significantly improved in the frequency range below 2,000 Hz. Our study highlights the importance of adjusting the concentration of particles and optimizing the cavity and pore structure of the material for achieving better sound absorption properties in PU composite foams.