The current design code for earth-rock dams （DL/T5395-2007）specifies that it applies only to earth-rock dams up to 200 m in height. With new developments in dam design and construction technology，design safety standards must be established for slopes of earth-rock dams more than 200 m high. Based on the theory of relative safety, the reliability index and safety factors associated with mapping should have the same platform.The permissible slope stability reliability indicator for a rolled earth-rock dam less than 200 m high, as specified by the current design code，is 4.2.Based on risk management principles，an allowable slope stability reliability indicator for a 200~250 m high earth-rock dam is 4.45，and that for a 250~300 m high earth-rock dam is 4.7.The corresponding slope stability safety factors for high earth-rock dams under seismic condition are 1.35 and 1.4，respectively.Slope stability safety factors for high earth rock dams under various seismic conditions were shown to meet safety standards.