Abstract: In order to investigate the flocking performances and sound insulating properties of nylon 66 fibers/aluminium alloy 6061 composite plates under different flocking technology conditions, aluminium alloy 6061 plates and nylon 66 fibers were composited to prepare the sound insulation composite plates by electrostatic flocking technology. Then, the effects of processing parameters such as flocking time, flocking voltage, plate distance and adhesive coating amount et al on flocking areal density and wearability of flocking fibers were investigated. Finally, the sound insulation properties of nylon 66 fibers/aluminium alloy 6061 composite plates under different frequencies of incoming audio and with different structural parameters of fibers were investigated by reverberation-anechoic chamber method. The results show that in the flocking time range of 0-40 s, the flocking areal density increases continuously with the flocking time increasing and then remains unchanged. While in the voltage range of 0-90 kV, with the increasing of voltage, flocking areal density increases continuously and then increases or decreases for the difference of plate distance. Wearability of flocking fibers increases with the increasing of adhesive coating amount, but after the coating amount surpasses 155 g/m², the gas bubbles generate. When the flocking time is 40 s, flocking voltage is 90 kV, plate distance is 11.5 cm and adhesive coating amount is 155 g/m², the nylon 66 fibers/aluminium alloy 6061 composite plates have the best properties. The composite plates have preferable sound insulating properties at medium and high frequencies, sound reduction index goes with the rule of 6 dB/octave within the frequency range of 500-1 600 Hz, and the tally effect occurs after 2 000 Hz. The sound reduction index of the nylon 66 fibers/aluminium alloy 6061 composite plates can be enhanced by increasing the flocking areal density and decreasing the nylon 66 fiber diameter. The research conclusions can lay the foundation for the development and application of new sound insulating composites used in architecture.