Rainfall erosion seriously threatens the stability of soil slopes and even induces failure. In this study, jute fiber and the microbial-induced calcium carbonate precipitation technique were combined to carry out ecological reinforcement of loess slopes. A simulated rainfall test was used to analyze the improvement effect and influencing factors of slope erosion resistance. Scanning electron microscope and energy dispersive X-ray spectrometer were used to analyze the mechanism of mitigating rainfall erosion on loess slope from a micro perspective, and to explore the feasible means of mitigating rainfall erosion on loess slope. The results show that: the addition of jute fiber can help to improve the rainfall erosion resistance of microbial-mineralized loess, especially for the medium and high content of medium and long size fibers; the fiber-reinforced loess treated by biomineralization can significantly resist the erosion of weak rainfall (6 mm/h) and short-term heavy rainfall (45 mm/h); under heavy rainfall conditions, the erosion resistance increases with the increase of fiber content, but the increase range gradually decreases, and the highest erosion resistance increases to 64.2%; with the increase of fiber length and fiber content, the thickness difference between C₂L₅ and C₈L₂₅ is 2.86 times. There are two cementation modes in the surface layer of fiber-reinforced microbial mineralized loess: the “intergranular filling” mode formed by the precipitation of calcium carbonate crystals in intergranular pores, and the “wrapped cementation” mode of calcium carbonate formed by wrapping soil particles through fiber connection.