With Fe₂O₃、CuO、Fe₃O₄、MoO₃ as oxidants, 50 nm or 5μm aluminum particle as reducer, twelve thermites were prepared by mixing them under ultrasonic shock. Structure and morphology of the thermites were studied by scanning electron microscope (SEM). The effects of oxidizer agent species and particle size of the materials on the reaction activity of thermites were studied by differential scanning calorimetry (DSC) and laser ignition. Results show that the dispersion of nanometer aluminum particle in MoO₃ is the best. The reaction order from high to low is Al/MoO₃ > Al/Fe₂O₃ > Al/CuO > Al/Fe₃O₄. When using nanometer aluminum particle, the critical reaction temperature of super thermites decreases 200-400 ℃, lower than that of micrometer aluminum particle. The critical reaction temperature decreases only 10-30 ℃ using nanometer oxidants, lower than that using corresponding micrometer materials. All the results indicate that particle size of aluminum particle is the key factor effecting the reaction activity of thermites, and ultra-refinement of oxidizer is only supplementary for the reaction activity of thermites. When the aluminum particle size locates on the same order, the reaction activity of thermites mainly depend on the species of oxidants.