Loess deposits in arid/semi - arid regions pose significant stability challenges for geotechnical engineering due to their loose structure and poor mechanical performance. Microbial - induced calcite precipitation (MICP) combined with biodegradable wool fibers offers a sustainable solution, but its synergistic reinforcement mechanism, long - term durability, and parameter optimization remain unclear. This study evaluated the static mechanical properties (unconfined compressive strength, shear strength), dynamic characteristics (hysteresis behavior, dynamic modulus, damping ratio), and long - term stability (90-day curing) of MICP - wool fiber co-reinforced loess, with microstructural validation via scanning electron microscopy (SEM) and X-ray diffraction (XRD). Key findings: (1) Static performance was optimized by 0.2 % fiber content (72.49 % higher short-term shear strength than unreinforced loess), 0.5 % fiber for long - term retention, 5 mm fibers for compressive uniformity/ 10-20 mm for shear enhancement, and bacterial concentration (OD600) shifting from 0.5 (short - term compression) to 1.0 (long - term shear). (2) Dynamic performance improved synergistically: co-reinforced specimens exhibited 1.70 - fold higher dynamic failure stress, 30 % prolonged elastoplastic stage, and balanced damping ratio (lambda = 0.0930) for seismic resilience. (3) A "self-compensating" degradation mechanism emerged: fiber-derived nutrients promoted 7 % calcite increment, reducing post - 90 - day strength loss by 14 % vs. fiber - only loess, with 444.12 % cohesion gain offsetting friction angle reduction. (4) SEM observations revealed that MICP precipitated 1-3 mu m thick, rhombohedral calcite crystals on wool fiber surfaces, increasing fiber-soil interface roughness by 300 % and eliminating gaps between fibers and loess particles; post-degradation, supplementary calcite filled 60 % of pores formed by fiber breakdown. XRD quantitative analysis confirmed calcite content increased from 7.8 % (unreinforced loess) to 17.1 % (90-day cured co-reinforced loess), directly linking mineral composition enhancement to improved mechanical stability. This work provides optimized parameters (0.5 % fiber/20 mm/OD600 = 1.0 for seismic regions; 0.2 % fiber/10 mm/OD600 = 0.5 for foundations) and a scientific basis for applying MICP - wool fiber co-reinforcement in loess engineering.