Abstract: Deducing the state of gas-solid two-phase flow from acoustic attenuation spectrum is an important approach to acoustic monitor and study of gas-solid two-phase flow.The expression of sound pressure level associated with propagation distance is deduced by assuming that the relative attenuation amount of sound energy is proportional to sound propagation distance.The experimental apparatus for measuring acoustic attenuation in gas-solid two-phase flow is established.According to the expression of sound pressure level,the expression for calculating acoustic attenuation index of gas-solid two-phase flow is also obtained.The background noise in experiments is mainly the noise caused by fans'vortex and rotation,as well as the mechanical noise and aerodynamic noise.The characteristics of different noise are analyzed,and the method of eliminating noise is proposed,by using A-weighting network and wavelet filtering to-gether.