Abstract: The environmental fatigue correction factor Fen considering the effect of pressurized water reactor (PWR) coolant environments on the fatigue life of materials was studied. Combined with the requirement of life extension of nuclear power plant, the fatigue analysis process based on environmental fatigue correction factor was established. For typical nozzle structure, the transformation strain rate and Fen were determined adopting the strain increment method of using stress time history of transient, and then the effect of environmental modification on the fatigue life was compared. After considering the environmental impact, the fatigue usage coefficient of austenitic stainless steel increases by 3.2 times and the fatigue usage coefficient of low alloy steel increases by 8.5 times. The effect of coolant environment on the fatigue life of materials is significant. The fatigue usage coefficients considering environmental impact were compared with the results of EPRI guidelines, the results are close to each other, and it is verified that the calculation method of environmental fatigue correction factor considering transient combination is correct.