The damping loss factor of a plate with damping treatment is measured by the impulse response method. The influence of the coverage ratio of the damping and the test condition on the damping loss factor of a plate is analyzed. The sound insulation of the plate is tested using anechoic-reverberation chamber, and the test results of the plate with different coverage of the damping material are compared. The calculation model of the sound insulation of the plate is established. The calculated values are in good agreement with the experimental data, which proves the validity of the model. Based on this model, the influence of the thickness and coverage of the damping material on the sound insulation performance of the structure is studied. Considering the characteristics of lightweight and sound insulation, the influence of the thickness and coverage of the damping material on the noise reduction efficiency is analyzed and the noise reduction optimization is carried out with the goal of maximizing the noise reduction efficiency.