The material composition of concrete affects the attenuation law of elastic wave characteristic parameters. The study of this law is of great significance for improving the accuracy of engineering safety detection. The plate-shaped concrete specimens are made of sand with 0.1~0.25mm, 0.5~1mm, 1~2mm and 2~5mm grain sizes, and the full waveform of the signals at different propagation distances is recorded by the acoustic emission measurement system, and the influence mechanism of particle size on the elastic wave attenuation process is analyzed. The results show that the amplitude of the elastic wave is attenuated by the negative exponential function, and the attenuation coefficients are 0.04375, 0.02579, 0.02185, and 0.01871, respectively, so the smaller the particle size is, the faster the attenuation of amplitude is. The elastic wave energy attenuation law is also in accordance with the negative exponential function, the smaller the particle size, the faster the energy decay rate. The decay rate of the elastic wave is closely related to the frequency. As the propagation distance increases, the main frequency of the signal and the center of gravity of the spectrum will gradually decrease, that is, the high-frequency signal decays faster. In addition, the count of acoustic emission is also roughly a logarithmic function decay.