Background <p>Initial shear stress and loading rate are two critical factors influencing soil mechanical behavior. Their coupled effects, however, remain insufficiently understood, particularly in terms of strength evolution and deformation mechanisms.</p> Objective <p>This study aims to investigate the coupling effects of loading rate and initial shear stress on soil shear behavior and to clarify their influence on strength characteristics and energy dissipation.</p> Method <p>A series of laboratory shear tests were conducted under varying initial shear stress levels and loading rates. Stress–strain responses, strength parameters, and energy components were systematically analyzed to quantify their coupled effects.</p> Result <p>The results indicate that both loading rate and initial shear stress significantly affect soil shear strength and deformation behavior. Increasing loading rate enhances peak strength, while initial shear stress alters stiffness and failure characteristics. Distinct energy dissipation patterns were observed under different coupled conditions.</p> Conclusion <p>The coupled influence of loading rate and initial shear stress plays a dominant role in governing soil shear behavior. These findings provide new insights into soil strength mechanisms and offer a theoretical basis for geotechnical design under complex stress and loading conditions.</p>