Abstract: The mechanical properties of soil are influenced not only by the current stress state but also by its stress history. Loess,a typical structural soil,exhibits complex mechanical behavior,and understanding its microstructural evolution under the influence of stress history is crucial. However,research on the impact of consolidation state on the microstructure of loess remains limited. This study uses triaxial consolidation experiments,scanning electron microscopy(SEM),and mercury injection tests to investigate the microstructural evolution of loess during isotropic consolidation. The results show that particle breakage characteristics under different consolidation pressures are not significant. As consolidation pressure increases,the anisotropy rate decreases,and the global orientation of the particle structure becomes less pronounced. The probabilistic entropy increases with higher consolidation pressure,indicating that the particle units become more chaotic and disordered. Additionally,the volume percentage of macropores and mesopores decreases from 42.1% to 2.6% ~3.8% as the overhead pores collapse under isotropic consolidation pressure. The volume percentage of small pores and the dominant pore diameter both decrease,while the volume percentage of micropores increases as intra-particle pores are compressed under increasing consolidation pressure. At higher consolidation pressures,the fractal dimension of pore increases and the pore surfaces become rougher and more complicated. Micropores with diameters less than 1 μm remain unaffected during consolidation. Furthermore,the particle arrangement characteristics under one-dimensional consolidation exhibit oriented alignment,while those under isotropic consolidation show a more uniform distribution. This highlights the importance of considering differences in particle arrangement and corresponding mechanical behavior under various consolidation conditions.