Based on experimental pattern and test results, exploding proceeding of two-charge at bottom in shallow-layer was simulated numerically. Comparisons of explosion processes of single-charge, two-charge exploding at bottom in shallow-layer water and two-charge exploding in infinitive water were made. Shock waves propagation and their interaction affected by bottom and free surface were analyzed. Affected by free surface and bottom, maximum value of shock-wave pressure and its impulse were reduced. During the reaction of two waves, blasting power must be increased.