The optimization of mixture proportion is determined by intensive tests based on designed index of the concrete in Three Gorges Dam. It is proved that the crack resistance of the concrete of the Dam is excellent by experiments and investigated results on site. The concrete is designed in a new method which is translated from traditional strength design into durability design. The effective additive and fly ash and moderate heat cement with micro-expansion are applied widely which enhance the capabilities of concrete essentially. So the long-term durability of the concrete in Three Gorges Project is ensured.