Abstract: Structural fatigue life contains crack initiation stage and crack propagation stage. Generally, crack initiation life and crack propagation life are calculated separately. Extended Paris model to a whole life prediction model based on Chaboche non-linear damage model, and build a relational model between nonlinear damage accumulation and crack length to analyze how a multi-level loading affect the damage accumulation. The results show that：When there is no initial crack, the Chaboche-Paris model analysis results are in good agreement with the S-N experimental results; when there is a macroscopic long crack, the results are in good agreement with the Paris model, which proves the accuracy and applicability of the model to predict both the two stages of the structural life. When add a two level loading, the Chaboche-Paris model can reflect the fatigue damage cumulative effect of the loading order, in the case of low-high loading, the sum o

Key words: life prediction;multi-level loading;full-life;crack propagation;non-linear continuum damage