The response surface method was used to optimize the mix ratio of industrial waste slag curing sand washing sludge, cement was added to improve the curing effect, and the composite curing agent of industrial waste slag was obtained. Through unconfined compressive strength test, water stability test and dry-wet cycle test, the effects of initial moisture content, curing age and curing agent content on the strength and durability of curing soil were studied, and the mechanism was analyzed by XRD and SEM. The results show that the optimal mix ratio (mass ratio) of slag, fly ash, calcium carbide residue and cement is 5.4∶1.7∶4.5∶2.0, and the curing effect is better than that of the same amount of cement. The synergistic effect of industrial waste slag and cement promotes the pozzolanic reaction. The strength and water stability of curing soil increase with the increase of age and content, but the strength decreases when the industrial waste slag composite curing agent content reaches 21.7% (mass fraction). The hydration reaction of CaO in calcium carbide residue improves the alkalinity of soil. The active aluminosilicate in slag and fly ash reacts in an alkaline environment, and the generated calcium silicate hydrate and calcium aluminosilicate hydrate fill pores and agglomerates soil particles. The dry-wet cycle provides high temperature conditions and moisture for specimen, and the strength of solidified soil is improved within a certain range.