In order to improve the mechanical properties of raw soil materials, iron tailings, gangue, calcium carbide slag, oil sludge and cement were used as admixtures to modify raw soil. On the basis of the monomorphic lattice method, the effects of different factors on the failure morphology, compressive strength and data discreteness of the specimen were studied through compressive test of 180 modified raw soil specimens of three modified formulas. Using the frequency analysis method, the optimal formula of solid waste modified raw soil material was studied. Then, the fractal and pore structures inside the loaded material were analyzed at a microscopic level through CT scanning. The results show that the compressive failure forms of different admixture-modified raw soil specimens are basically the same, but the admixture significantly affects the limit displacement. Gangue and calcium carbide slag, iron tailings and cement, oil sludge and cement as raw soil admixtures can greatly improve the mechanical properties of modified raw soil specimens, the type and the amount of admixture have a significant impact on the strength and data discreteness of modified raw soil specimens. After frequency optimization, the ideal strength admixture ratios for the three formulas are 1) iron tailings 12.1%~19.5% (mass fraction, the same below), cement 13.9%~19.1% and raw soil 65.5%~69.9%; 2) calcium carbide slag 6.7%~14.1%, coal gangue 8.9%~11.8% and raw soil 76.7%~81.8%; 3) oil sludge 11.4%~14.4%, cement 17.4%~19.4% and raw soil 67.1%~70.5%. The fractal and pore characteristics inside the material are stable, exhibiting small fluctuations and good compactness.