A large number of landslides and collapses are often triggered by earthquake, but little attention has been paid to the risk assessment of glacier lake outburst under coaction of earthquake and ice avalanches. To investigate the characteristic of hydrodynamic pressures under coaction of earthquake and ice avalanches, experimental analysis of hydrodynamic pressures were conducted under separate earthquake action and ice avalanches action, respectively. The ice block sliding into the reservoir was added during the process of earthquake simulated by shaking table, the characteristic of combined hydrodynamic pressures caused by earthquake and ice avalanches were then observed. The results show that the seismic hydrodynamic pressures were decreased from the bottom to the top, which was in good agreement with Westergaard's briefly solutions. However the hydrodynamic pressures caused by ice avalanches were increased from the bottom to the top. Meanwhile the effect of the volume,the sliding block velocity and initial water depth were considered to study the characteristics of the hydrodynamic pressures, and an empirical equation was obtained to predict the maximum pressure loads acting on the dam. The hydrodynamic pressure distribution curves under coaction of earthquake and ice avalanches were approximately equal to the superposition of separate earthquake and ice avalanches actions,but the combined values were smaller than the superposition values, and the estimation method of maximum hydrodynamic pressure was proposed.