To investigate the propagation characteristics of shock waves generated by underwater explosion constrained by different bottom sediments， this study designed 10 working-condition principle experiments of underwater explosion， covering three typical bottom sediment （concrete， sand， and clay） and varying burst heights.The shock wave pressure time-history curves of underwater explosion at different typical measuring points were collected， and the propagation characteristics were compared and analyzed. The experimental results show that when the dimensionless burst height parameter γ=0， There exists a positive correlation between the wave impedance of bottom sediment and the reflection effect of shock waves. The reflection coefficient of shock wave peak pressure on concrete markedly exceeds that of sand and clay， with corresponding maximum values of 1.337， 1.195， and 1.158 for the three sediments， respectively. Measurement azimuth exerts a significant effect on shock wave pressure propagation： the average reflection coefficient of shock wave peak pressure in the 60° direction is higher than that in the 30° direction， with the improvement amplitudes for concrete， sand， and clay reaching 25.01%， 16.44%， and 41.77%， respectively. For near-bottom explosions， the influence of bottom sediment gradually weakens with increasing burst height. When γ=0.5， the maximum reduction in the average reflection coefficient reaches 17.05% for concrete in both 30° and 60° directions and for sand and clay in the 30° direction， while the maximum increase reaches 6.65% for fine sand and clay in the 60° direction. When γ=1， the observed variation trend is consistent with that at γ=0.5， the maximum reduction in the average reflection coefficient reaches 21.37% for concrete in both 30° and 60° directions and for sand and clay in the 60° direction， while the maximum increase reaches 31.68% for sand and clay in the 30° direction， and the reflection coefficient in all directions approaches 1. Based on these results， it can be inferred that the influence of bottom sediment on shock wave pressure propagation will decrease rapidly when γ> 1.