Abstract: A novel steel slag-based binder is used to solidify/stabilize the contaminated clay with nickel (Ni) and zinc (Zn). The effects of wetting-drying cycles on the mass loss rate, unconfined strength and leaching characteristics of the treated soil are studied by modified wetting-drying cycle tests. The results demonstrate that with the increase of wetting-drying cycles, the change rate of leaching concentration of heavy metals and the relative cumulative mass loss rate of the treated soil both decrease at first and then increase with the lowest values are -3.23%, -4.29% and -1.06%, respectively, while the change rate of unconfined compressive strength of the treated soil exhibits an opposite trend with the highest values is 27.25%. When the deterioration of the treated soil happens, the number of the critical wetting-drying cycles corresponding to the change rate of the leaching concentration of heavy metals is 6, while the number corresponding to the change rate of the relative cumulative mass loss and unconfined compressive strength is 18.