Abstract: Load-controlled creep-fatigue (CF) tests were conducted for X12CrMoWVNbN10-1-1 steel at 620 ℃ to verify the creep-fatigue life prediction model based on strain energy density, while an analysis was carried out on the creep strain, the elastic strain and the plastic strain characteristics of the steel. Results show that the process of X12CrMoWVNbN10-1-1 steel under CF load condition consists of three stages. The strain energy density at stable stage is inversely proportional to the total strain energy density dissipated by X12CrMoWVNbN10-1-1 steel, and the total strain energy density under different test conditions is proportional to the fatigue life, therefore the expression of the strain energy density at stable stage could be chosen to predict the fatigue life. The model obtained from the load-controlled CF test of X12CrMoWVNbN10-1-1 steel with short holding time may be used to predict the fatigue life of the steel with long holding time, indicating that the life prediction model based on strain energy density is also applicable to X12CrMoWVNbN10-1-1 steel.