Steel slag and ground granulated blast-furnace slag are two common industrial waste slags, which are piled up in large quantities and are difficult to use as resources. Using steel slag powder and blast-furnace slag powder as basic materials, and calcium carbide slag powder as activator， the muddy soil was solidified. The strength characteristics and stress-strain relationship of solidified muddy soil by carrying out unconfined compressive strength tests were analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) microscopic tests were used to explore the mechanism of calcium carbide slag activated steel slag and ground granulated blast-furnace slag solidified muddy soil. The results show that when the content of calcium carbide slag powder is 6%, the unconfined compressive strength of calcium carbide slag-steel slag-blast furnace slag solidified muddy soil is the highest. The 28 d solidified muddy soil has the same strength as cement solidified muddy soil of the same age and has good ductility. Calcium carbide slag provide an alkaline environment and a large amount of calcium ions, effectively stimulate the hydration activity of steel slag and blast furnace slag, promote the mass production of C-S-H gel, and promote ion exchange and agglomeration, so that the strength of solidified muddy soil is significantly improved.