Nuclear fuel cladding is subjected to neutron irradiation in a high-temperature stress environment, and the structural integrity of the cladding is very important for the safe operation of nuclear reactors. FeCrAl alloy has become a promising candidate cladding material for the accident tolerance fuel development in view of its excellent irradiation resistance and high temperature strength. This work aims to study the creep properties of FeCrAl alloy at high temperatures under neutron irradiation. Thermal and irradiation creep behavior in nanocrystalline FeCrAl samples is examined using molecular dynamics simulation method. And the effects of temperature, stress, irradiation dose rate on the creep rate and parameters of the creep constitutive equations are discussed. The results show that the thermal creep rate is greater than irradiation creep rate. The effect of temperature on the thermal creep stress exponent is relatively small at low stress, but is obvious when stress exceeds 0.8 GPa. The higher the temperature, the larger the thermal creep stress exponent. The irradiation creep rate increases almost linearly with the dose rate, that is, the exponent of dose rate for irradiation creep approach 1.0. Irradiation creep stress exponent fluctuates very little around 1.1 within the scope of the present research. Besides, higher temperature accelerates the linear increase of irradiation creep rate with dose rate, and the irradiation creep pre-factor becomes higher.