Abstract: The super high cycle fatigue property of FV520B-I steel was studied by ultrasonic and conventional fatigue test method with frequency of 20 kHz and 140 Hz, respectively. The influence of loading frequency on super high cycle fatigue property of FV520B-I steel was investigated, and the ultrasonic fatigue testing data was corrected based on Basquin formula. The results show that the fatigue life of FV520B-I steel increased with increase of loading frequency when stress amplitude was the same, while fatigue strength was decreased. The fatigue fracture mechanism and fracture morphology of FV520B-I steel in ultrasonic fatigue test were almost the same with that in conventional fatigue test. The corrected ultrasonic fatigue test data had a good compatibility with conventional fatigue test data.