A new equation for fatigue life prediction considering the stress ratio was established. The expression introduced a new parameter which reflected the effect of stress ratio on the stress gradient exponent based on the previous fatigue life model with stress gradient. Life prediction and precise checking were carried out using exiting test data of typical alloy. The results showed that the local stress ratio had a considerable influence on the stress gradient exponent. The calculation results of the modified model were more close to the experiment results than the previous model. Predictions of notched specimens for TC4(200 ℃) and GH4169(500

650 ℃) showed a scatter band within 2.0. Even better

some of the results showed a scatter band within 1.5.