The engineering properties of yellow floodplain silt are poor, and it needs to be solidified before it can be used as a roadbed fill material. However, traditional solidification solutions require large amounts of cement, and the cement production process consumes large amounts of energy. To solve this problem, silica fume (SF) and ground granulated blast furnace slag (GGBS) were used as precursors, and carbide slag (CS) was used as an exciter, based on the Box-Behnken design (BBD) test in the response surface methodology, to compare and analyse the effects of different mix ratios of silica fume-ground granulated blast furnace slag-carbide slag (SGC) cementitious materials and cement on the mechanical properties and water stability of loess in yellow floodplain, and the microscopic solidified mechanism of the cured soil was explored by using X-ray diffraction (XRD) test and scanning electron microscope (SEM) test. The results show that the optimal mass mix ratio of silica fume, slag and calcium carbide slag is 5.94%∶21.87%∶4.31%. The 7、 28 d unconfined compressive strength of solidified soil under this ratio is 6 531.58 and 9 269.26 kPa, respectively, which increase the 7, 28 d unconfined compressive strength by 28.3% and 21.4%, respectively, compared with that of the cement solidified soil. SEM and XRD test results show that the main hydration products of SGC solidified soil are cementitious materials such as calcium silicate hydrate (C-S-H) and calcium aluminates hydrate (C-A-H), and the micro-morphology of SGC solidified soil at the age of 28 d is more compact than that of cement solidified soil. The effect of SGC stabilizer on the improvement of loess in yellow floodplain is significant, and it has good engineering application value.