Fatigue life estimation of aero-engine turbine components under combined high and low cycle fatigue (CCF) is of significance for guaranteeing the structural reliability during operation. According to the investigations on damage evolution process, a nonlinear damage accumulation method is proposed for life prediction under CCF loadings, and the interaction effect between high cycle fatigue (HCF) and low cycle fatigue (LCF) is considered by integrating the interaction factor and stress ratio of CCF. Furthermore, experimental results of alloys and turbine blades are utilized to validate the proposed method and conduct a comparative analysis among Miner’s rule and other two typical nonlinear cumulative damage methods under combined loading conditions. Comparative results demonstrate that the developed model holds better prediction robustness and accuracy than those of others.