Abstract: To address the issue of excessive environmental noise in laboratories, a new type of sound-absorbing composite board was developed. The board has a composite structure consisting of a perforated plate, melamine foam, an asphalt damping layer, glass wool, and a rigid backing (including a skeleton). It exhibits a sound absorption coefficient of no less than 0.6 in the frequency range of 100-5000 Hz. Firstly, Biot's theory was introduced to establish the sound transmission model of the composite board under random incidence of sound waves, and finite element methods were employed to compute the simulation results. Subsequently, a sample of the board was placed in a reverberation room to test its sound absorption coefficient. The test results were consistent with the simulation results, confirming the feasibility of the model. Finally, the sound-absorbing composite board was applied in the environmental noise control project of the Guangzhou Institute of Metrology's thermal laboratory, successfully reducing the indoor noise A-weighted sound pressure level from 79.8 dB to 64.1 dB, further validating the high sound absorption performance of the new sound-absorbing composite board.