Abstract: Rigid and flexible boundary conditions constitute the two predominant types of conditions encountered in roadbed construction, each having a substantial influence on the deformation and settlement characteristics of the foundational soil. Utilizing custom-designed triaxial loading apparatus, this research conducts a series of indoor compression tests on compacted loess with varying degrees of compaction, under both rigid and flexible boundary conditions. The investigation aims to unravel the effects of these conditions on the deformation behavior of compacted loess, as well as to identify the fundamental mechanisms contributing to variations in deformation. Our findings reveal that the compressive strength of loess-tested at compaction degrees of 88%, 93%, and 96%-exhibits a positive correlation with the degree of compaction during triaxial compressive loading under both types of boundary conditions. Moreover, under constant compaction degree, an increase in confining pressure results in a reduced reduction in compaction. The study further delineates equations for the relationships between vertical and volumetric strains, as well as between vertical and lateral strains.