Abstract: To investigate the operating conditions of China demonstration fast reactor power plant, the conventional island thermal system simulation model was established on the vPower platform, and then several typical operating conditions for conventional island were simulated. The operating key parameters of steady state operating conditions were given by simulations, and they are no more than 1% off the design values, which meet the demanded accuracy of nuclear power simulation. High-pressure feedwater heater splitting and steam turbine emergency shutdown were simulated, and the transformation law of key parameter and information of the possible danger point were given.