Abstract: The effects of Fe element on the structures and chemical stability of simulated nuclear waste immobilized by the thermit self-propagating high temperature synthesis (SHS) were investigated. The composition, microstructure, thermal stability, and the normalized release rate of the products were characterized by X-ray diffraction, scanning electron microscope, thermogravimetric and differential scanning calorimeter analysis, and product consistency test (PCT). The results show that the dominant crystalline phase of the immobilized SHS products is Al₂O₃, and Fe has no significant effect on the composition and structure of the products. The products have dense and well-developed crystal structure. But the apparent porosities and apertures increase with Fe content. The products also have good thermal stability without obvious weight loss at the temperature lower than 1 400 ℃. The leaching rate of Ce during 28 days is 10^-5-10^-6 g/(m²•d), and there are no significant changes in the normalized release rates of Ce, Ca, Si, Al and Fe when the Fe content of the products increases from 1% to 10%.