The numerical simulation of cavitation flow on a 2D NACA0015 hydrofoil under high pressure and temperature is performed. The Singhal’s cavitation model is adopted combined with an improved RNG k-ε turbulence model to study the cavitation flow. The thermal effect in the cavitation flow is taken into account by introducing the energy equation with a source term based on the latent heat transfer. The code is validated by a case of a hydrofoil under two different temperatures in a comparison between the simulation and the experiment. Computational results show that the latent heat of vaporization has a significant impact on the cavitation process in the high temperature state, and the cavity in the high temperature state is thinner and shorter than that in a normal state with the same cavitation number, due to the fact that the heat absorption in the cavitation area reduces the local temperature and the saturated vapor pressure. This numerical study provides some guidance for the design of machineries in the High Pressure and Temperature (HPT) state.