In this work, ceramsite was utilized to fabricate the sound-absorbing boards, in which two types of structure were considered, specifically, single-layer board with homogenous structure and double-layer board with gradient structure. The physical, mechanical and acoustic properties of these prepared ceramsite sound absorbing boards were studied, including the bulk density, compressive strength, flexural strength, softening coefficient, sound absorption coefficient and sound reduction index. The results show that the double-layer board with appropriate mixture design exhibited almost identical bulk density and mechanical strength to the single-layer board. All ceramsite sound absorbing boards had compressive and flexural strengths of more than 3 MPa and 1 MPa, respectively, and also demonstrated good water resistance. In terms of sound absorption and sound insulation properties, the overall performance of the double-layer board with reasonable gradient structure was better than that of the single-layer board. In addition, the physical structure models of ceramsite sound absorbing boards were established to illustrate the variation of mechanical properties and disclose the mechanism of sound absorption and insulation in the material.