Abstract: The sound attenuation performance of dissipative silencer with acoustical splitters depends on the sound absorption coefficient of the absorption sheet. The detailed analysis of the influence of the middle baffle in acoustical splitters on the absorption coefficient is of great significance to the design and application of the silencer. Based on the transfer matrix method and the sound wave propagation theory in sound-absorbing materials, a calculation model of absorption coefficient of the multi-layer absorption plates in silencer is established. The sound absorption coefficients of different absorbing channels in silencer are calculated. By comparing and analyzing the sound absorption coefficients of different absorbing channels, the influence of the middle baffle on the sound absorption performance of the dissipative silencer is discussed. Taking the actual silencer as an example, the comparison between calculated sound absorption coefficient and the measured insertion loss shows a good agreement with each other in the trend of frequency change. It is verified that the effect of the middle baffle in acoustical splitter on attenuation performance is different in different frequency ranges. In the low frequency and higher frequency range, the baffle plate plays a positive role, but in the middle frequency range, the baffle plate plays a negative role.