Abstract: The energy dissipation and entropy at the shock wave front of underwater explosion are theoretically analyzed. First, the propagation of underwater shock wave in space is obtained by using the characteristics of shock wave velocity trajectory. Then the theoretical model of the entropy and energy dissipation during the propagation of underwater shock wave is established. For the explosives of TNT and RS211, the analysis of the entropy and energy dissipation in the near field of underwater explosion was carried out with presented theoretical model. The research results predict in theory that the entropy and energy dissipation occurs mainly in near field of the interface of water and explosive charge about 10 times of explosive charge radius. For the explosives of TNT and RS211, the value of total energy dissipation is about 34% and 32% of the total energy released from the explosives at the 20 times of explosive charge radii, respectively. Above conclusion is basically corresponding with the underwater explosion experimental results.