In order to analyze the motion law, shape change and damage effect of the shaped-energy jet in the water medium, the numerical simulation of the shaped-energy jet formed by the shaped-energy warhead of the cone-shaped charge-shaped cover structure is carried out. Under the condition of considering the hydrostatic pressure, AUTODYN is used to numerically simulate the shape change, velocity attenuation and penetration effect of the target plate when the shaped energy jet penetrates the water medium at 1 m, 10 m and 50 m underwater, and it is compared with the jet formed in the air at the same height. The results show that the jet head will accumulate obviously as the water depth deepens; the velocity decays linearly in the cavity and exponentially decays in the water medium; under the same explosive height conditions, the penetration aperture of the concentrated jet in the water into the target is larger than that in the air.