Abstract: The energy deposition of underwater electrical explosion of a copper wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrating Rogowski coil and a voltage divider were used for the measurements of the current and voltage on the wire load, respectively. Three stages of melting, liquid state and vaporization were defined by the definition of four critical time points, i.e. the beginning of melting, the end of melting, the beginning of vaporization and the beginning of breakdown. The deposited energy in the three stages and before breakdown was calculated by mathematical method. The effects of circuit parameters, including applied voltage and circuit inductance, and the properties of copper wire consisting of the length and diameter on deposited energy in the three stages and before breakdown were analyzed by experiment and calculation. The influence of circuit parameters and properties of copper wire is in significant in the melting stage, and obvious in the stages of liquid state and vaporization. By adjusting circuit parameters, the deposited energy in the stage of liquid state and before breakdown obviously increases with the increase of the current rise rate.