Abstract: The calculation principle,configuration,validation process and result of CPR1000 nuclear reactor power calibration system are introduced.Based on IAPWS-IF97,which is a model of water and steam thermodynamic properties,and enthalpy difference-thermal power theory,CPR1000 nuclear reactor power calibration system is used for calculating the thermal power of nuclear steam supply system and the nuclear power of the reactor.The calibration system was used during the start-up of unit 3 of Ling’ao NPP,and on-line calibration for reactor power measuring and control system had been conducted successfully.It is proved that CPR1000 nuclear reactor power calibration system can be used to calibrate the reactor power measure and control systems reliably.