Abstract: A comparative numerical simulation analysis was conducted via the software ANSYS/LS-DYNA on the charge structure between gun hole at the bottom of the water space and the normal blasting structure. The results showed that the water cushion at the bottom of the step blast holes makes explosive energy in blast holes a more even distribution，which lengthens the action of the stress wave in rock mass，and benefits to break the bench rocks. The specific application of the research finding above makes a good blasting effect and thus brings a reference for further study of the water pressure blasting theory and field applications.

Key words: Water media, Water bearing blasthole, Bench blasting, Numerical simulation