In order to investigate the effect of fine zirconium powder with diameter of 1 μm on the reaction mechanism of KClO₄ during thermal decomposition, TG/DTG and X-ray photoelectron spectroscopy (XPS) analysis were applied to determine the thermal behavior of KClO₄ and Zr/KClO₄ (50:50). The result of XPS shows that the addition of KClO₄ promoted the reversible chemical reaction equilibrium of KClO₄. Linear regression was used to determine the kinetic triplet. The calculation result shows that the activation energy declined while the pre-exponential factor increased and the mechanism function shifted from G(α)=[-ln(1-α)]^3/4 to G(α)=-ln(1-α), the critical temperature of thermal explosion declined from 587.7 ℃ to 516.9 ℃ for the first decomposition stage. As for the second one, the activation energy increased while the pre-exponential factor hardly changed and the mechanism function remains G(α)=-ln(1-α). Thus it can be inferred that zirconium accelerated the first thermal decomposition step of KClO₄, increased the number of active sites and made it easier to happen, but became inert substance since it was oxidized to ZrO₂ and that was the reason of the increment of the activation energy and the invariant of the mechanism function.