Abstract: To comprehensively investigate the three-dimensional mechanical behavior of unsaturated saline loess under the combined effects of pore water salinity (osmotic suction) and matric suction, a series of isotropic compression and consolidated drained shear tests at p-constant & b-constant are conducted on loess with varying salinity levels using an unsaturated true triaxial apparatus under suction-controlled conditions. The study examines the influence of salinity on the deformation and failure strength characteristics of unsaturated loess. Additionally, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) are employed to explore, from a microscopic perspective, the mechanisms by which salinity-induced changes in pore morphology and pore size distribution affect macroscopic mechanical behavior. The results indicate that as salinity increases, the micropores in the loess contract while the macropores expand, leading to enhanced compressibility and a reduction in yield stress. During loading, the salinity-induced enlargement of macropores makes them more prone to collapse, which facilitates an increase in the effective contact area between particles and ultimately enhances the shear failure strength. Based on the results, empirical expressions for yield stress and critical state line strength parameters, accounting for both osmotic and matric suction effects, are established. These expressions provide a theoretical reference for understanding the evolution of mechanical properties in infrastructure constructed in saline loess regions.