Clarifying the mechanical properties of solidified oil-contaminated soil and the evolution of contaminate migration and diffusion under environmental effects is a key prerequisite for promoting the reuse of contaminated soil projects. Lime and fly ash with a low-carbon concept were selected as solidification materials, combined with the leaching test and COMSOL Multiphysics software, the control of the solidification effect on oil migration under leaching environment was evaluated macroscopically by oil content after leaching, and the mechanical stability under seepage was evaluated by soil strength and deformation. The results indicate that the solidification of lime fly ash can solve the problem of contaminant migration and diffusion or even a large number of migration under the leaching effect of contaminated soil, and achieve good control of the migration of oil contaminants in soil. The oil content at the interface of solidified contaminated soil under the action of seepage leaching is always close to the initial oil content setting state, and the change rate mobility is only 1.35 % ~ 2.76 %. The variation range of mechanical parameters of solidified contaminated soil under leaching is positively correlated with confining pressure and contaminant concentration, but only fluctuates within 10 s of initial stress and then the strength value is stable at 5.77×104 ~ 6.07×104 N / m2, and the maximum fluctuation value of displacement is 1.73×10-3 ~ 6.46×10-2 mm. The mechanical stability of solidified contaminated soil is good, and the safety factor (Fs) is more than 10. Lime fly ash solidified oil contaminated soil can take into account both environmental and engineering requirements, and has the potential for engineering reuse.