Abstract: A modified combined high and low cycle fatigue life prediction model was established based on Manson-Halford model by studying the damage equivalence relationship between high cycle fatigue and low cycle fatigue, and introducing an influence factor to reflect the influence of the interaction between high cycle fatigue and low cycle fatigue loads. The modified model was verified by the test data of TC11 titanium alloy, LY12-CZ aluminum alloy, 45 steel and GH4033 nickel-base alloy. The results show that the fatigue life prediction results of TC11 titanium alloy, LY12-CZ aluminum alloy and GH4033 nickel-base alloy by using the modified model were within the range of two times of error. About 78% of the predicted fatigue life of 45 steel was in the range of two times of error. The modified model had high prediction accuracy and was suitable for the prediction of high and low cycle composite fatigue life.