<p>This study focuses on the effect of initial stress state on the dynamic behavior of saturated loess. A series of undrained dynamic triaxial tests were conducted to investigate the cyclic failure mode, deformation behavior and cyclic degradation of saturated loess under different static and dynamic stress conditions. The results indicate that the cyclic failure mode and deformation behavior of saturated loess are governed by the initial stress state. Under isotropic consolidation, stress reversal occurs during cyclic loading, triggering flow liquefaction; this is accompanied by significant double-amplitude strain, with deformation evolving from slight compression to tensile collapse. Under anisotropic consolidation, by contrast, no or only partial stress reversal occurs, leading to the accumulation of compressive plastic strain and eventual failure via cumulative deformation. Fitting of the modified hyperbolic model to <i>G</i>/<i>G</i>_<i>max</i>-<i>γ</i> relationship reveals that confining pressure, consolidation stress ratio, and dynamic stress amplitude have certain influences on shear modulus degradation. Normalizing shear strain by the reference shear strain (<i>γ</i>/<i>γ</i>_<i>r</i>) effectively mitigates the dispersion of the<i> G</i>/<i>G</i>_<i>max</i>-<i>γ</i> distribution; thus, the<i> G</i>/<i>G</i>_<i>max</i>-<i>γ</i>/<i>γ</i>_<i>r</i> relationship can be adopted as a unified estimation basis for the normalized shear modulus of saturated loess. The findings of this study hold significant implications for advancing the understanding of the dynamic characteristics of saturated loess and enhancing earthquake disaster prevention and mitigation in loess regions.</p>