The research background focused on the occurrence of loess roadbed landslides in northwest China in recent years. The test datas of solidified loess with different geopolymer content were measured through compaction and direct shear tests. Additionally， the microstructure of steel slag-fly ash geopolymer solidified loess was examined using the scanning electron microscope （SEM） test and X-ray diffraction （XRD） test， and the pF-Meter instrument was used to measure the matrix suction and volumetric moisture content of the solidified loess with different geopolymers content. The test datas were then imported into COMSOL Multiphysics based on the strength reduction method， and the finite element model of the solidified loess roadbed slope was created using the Richards equation of the saturated-unsaturated theory. The impact of geopolymer content and slope ratio in the roadbed layer on the overall stability of the roadbed slope before and after rainfall was analyzed. The results indicate that when the solidified loess contains 25% geopolymer， the internal friction angle increases by 62.5% compared to reshaped loess， reaching 31.2°. The cohesion exhibits a trend of initially increasing and then decreasing as the geopolymer content increases. The highest peak is reached at 81.09 kPa when the geopolymer content is 20%， which is 75.86% higher than the cohesion of reshaped loess. The stability of the roadbed slope initially increases and then decreases with an increase in geopolymer content， while it increases with a decrease in slope ratio. Under specific conditions， slope stability decreases with prolonged rainfall duration and reduces with higher rainfall intensity.