<p>In order to explore the energy dissipation mechanism of shaped charge jet in underwater forming process. The finite element model of shaped charge jet underwater forming was established, and the difference of energy distribution of shaped charge jet in water and air was analyzed. Based on the virtual origin theory, the key time parameters of shaped charge jet fracture and fusion were introduced, and the theoretical model of energy dissipation of shaped charge jet underwater forming was established. The shaped charge jet underwater forming experiment was designed and carried out, and the changes of shaped charge jet shape and cavity were captured. The results show that the formation process of shaped charge jet in water can be divided into three stages: continuous stage, rupture stage, and fusion stage. Compared with air medium, the jet shape formed in water is quite different, and the jet velocity of shaped charge is 12% higher than that in air. The energy of shaped charge jet decays exponentially after entering the water, and 63% of the energy is consumed in a short time after entering the water, and then tends to be stable. The relative error between numerical solution, theoretical model, and experimental results is less than 15%, showing good consistency. The theoretical model can predict the energy dissipation under the shaped charge jet.</p>