By choosing two types of explosives GH-1 and GUHL-1, and two typical dual charge structures, the test samples were prepared. The characteristics of energy output of underwater explosion for dual explosive charge were studied and compared with that of the single explosive charge. The results show that under the same composition, the dual explosive charge can change the explosion load near the testing point, and decrease the energy loss of shock wave in the detonation propagation. By using dual explosive charge structure with a non-ideal explosive as an inner core surrounded by a high detonation velocity explosive, the bubble energy is increased by 22.4% compared with that of the single explosive charge, and also energy coupling exists in the two parts of the charge.