Abstract: Ultra high arch dams have higher stress levels and higher requirements of integrity, safety and durability of concrete dam bodies, which requires dam concrete to have higher strength grade, penetration resistance, frost resistance, and crack resistance. In this study, we have developed a specific low heat Portland cement that is suitable for the production of such dam concrete for ultra high arch dams. For this new type of cement, suitable contents of its four major mineral components were determined by considering the comprehensive effects of cement mineral composition, material strength and hydration heat. Its MgO content was controlled in the range of 4% - 5% to compensate thermal shrinkage during concrete temperature drop, and its specific surface area was limited to no greater than 340 m2/kg to reduce cement hydration rate at early stage. A new standard, Technical Requirements of Low Heat Portland Cement for Arch Dams, is suggested in this study and the corresponding design criteria are set to control cement quality. The dam concrete made of the specific cement that meets this standard will have a satisfactory performance in low unit water consumption, low adiabatic temperature rise, and high crack resistance. For this specific cement, a management and supervision system of quality control for the whole procedure has already been established and its large-scale steady production is achieved. Thus all this has laid a solid basis for application of low heat Portland cement in construction of 300m high arch dams and other hydropower projects.