Abstract: In order to research the energy deposition micro-specialty of proton in body-tissue or tissue equivalent material, the water vapor was adapted to be the tissue equivalent material based on the analysis of the body-tissue. The Monte-Carlo method was used to simulate the behavior of proton in the tissue equivalent material. The value in every energy deposition events is in the range of 0～50 eV by analyzing the data from calculation. The proton track is composed of these energy deposition events.