The environmental effect of solidified contaminated soil is an engineering issue that needs to be studied in the process of waste soil reapplication. Taking cadmium, lead and nickel contaminated soil as the research object, through the initial screening of the curing rate index, the suitable curing material ratio, simulating wetting and drying cycles, long-term water immersion, high temperature, freeze-thaw cycles environment, and evaluate the environmental effects of soil after cement, cement+fly ash and lime solidification by the leaching toxicity index, combined with microscopic and heavy metal morphology analysis, evaluate the instability mechanism. The result shows that inorganic materials can increase the solidification rate of heavy metals to more than 90%, 8% lime is suitable for the solidification of cadmium contaminated soil, and 32%+8% cement+fly ash is suitable for lead and nickel contaminated soil. Solidification of contaminated soil under water environment (wetting and drying , water immersion) has no environmental risk, and its leaching toxicity is lower than the limit in the Identification standard for hazardous wastes: Identification for extraction toxicity (GB 5085.3—2007); but solidification contaminated soil is sensitive to temperature (high temperature, freeze-thaw), especially cement, cement+fly ash solidified contaminated soil, when the temperature exceeds 70 ℃, the leaching toxicity exceeds the standard limit, and it is close to the freeze-thaw cycles 5-7 times the standard limit. High temperature will promote the transformation of the occurrence of heavy metals from a stable state to an unsteady state. The freeze-thaw cycles will destroy the structure of the heavy metal-solidified product system. The application of inorganic materials to solidify heavy metal contaminated soil needs to consider the influence of environmental temperature.