[Objective] To analyze the macroscopic and microscopic mechanisms of loess strength degradation under the coupling of wet and dry cycles and soluble salt content, and to provide a basis for engineering construction and geologic disaster prevention and control in the Yili region. [Methods] Taking typical loess in Yili area as the research object, we analyzed the effects of different numbers of dry and wet cycles and different soluble salt contents on the mechanical properties and microstructure of loess by triaxial shear test, scanning electron microscope (SEM) test and nuclear magnetic resonance (NMR) test. [Results] Triaxial shear tests revealed that cohesion decreased by approximately 17.5% after only 10 freeze-thaw cycles (η=0%). When soluble salt content increased from 0% to 2% (N=0), cohesion decreased by about 3.5%. However, under their coupled effect (N=10, η=2%), cohesion decreased by 24.3%, demonstrating a significant synergistic deterioration effect. Soluble salts exerted a highly significant influence on both cohesion and internal friction angle, while wet-dry cycling had a highly significant effect on cohesion and a significant effect on internal friction angle. Under low confining pressure conditions, the failure mode of loess shifted from brittle to plastic failure; under high confining pressure, although maintaining relatively high strength, it continued to deteriorate. SEM analysis revealed that with increasing wet-dry cycles and soluble salt content, fracture development occurred, gradually increasing the loess's porosity fractal dimension and pore area ratio. NMR analysis showed a significant increase in T2 peak amplitude, with corresponding T2 relaxation times gradually lengthening. This indicates a reduction in micropores coupled with a sharp expansion of mesopores and macropores, leading to increased porosity and enhanced connectivity within the pore system. [Conclusion] This study elucidates the macro-micro mechanisms of loess degradation under coupled dry-wet cycling and soluble salt conditions. The fundamental cause of strength reduction and structural deterioration in Ili loess stems from the combined effects of repeated swelling and shrinkage driven by dry-wet cycling and crystallization stress induced by salts. This research provides new experimental evidence for regions with similar soil and climate characteristics, laying a theoretical foundation for engineering design and geological hazard prevention.