Abstract: In case of gas cutting,hydrate is likely to form in deep water blowout preventers due to low temperature and high pressure and block the blowout preventers,which might compose safety threat at wellhead.Combining deepwater drilling conditions,3D models of ram preventers and annular blowout preventers in deepwater drilling condition were built-up,and numerical simulation of temperature field was performed to obtain the temperature distribution across the preventer.Then optimal heating locations of pipes were chosen according to the effect of heating pipe on blowout preventer temperature field.Result showed in the simulated temperature that heating by annulus itself in the transverse direction of the ram BOP,and heating pipe around 1/4 part of the longitudinal section could meet the requirements of preventing gas hydrate formation.Quantity of heating pipes has large influence on the temperature field of annular BOP.Optimization of pipe quantity and insulation combination should be considered to keep the temperature at annular BOP over hydrate formation temperature.