To simulate heterogeneous catalysis reaction process of chemical non-equilibrium gas on surface of hypersonic aircraft, further improve the prediction accuracy of aerodynamic heating, a kinetic Monte Carlo (KMC) model for multi-step reaction of heterogeneous catalysis was developed based on the chemical kinetics mechanism and property parameters of silica-based material. Surface adsorption, ER/LH recombination and thermal desorption were involved in the model. KMC method selects the next reaction step according to the frequency of collision and probability of reaction. Reaction results based on the catalytic model showed that LH recombination was accompanied by spatial effects, which was more significant at higher wall temperatures. Because the spatial effect, coverage of atomic oxygen predicted by the KMC model was lower than that by model based on the assumption of mean-field adsorption, which was also more significant at higher wall temperatures. Moreover, both recombination coefficients of ER and LH mechanism first increase and then decrease with the increase of wall temperature. KMC model could provide accurate catalytic boundary condition for the macroscale CFD prediction of aerodynamic heating. Furthermore, it provides theoretical support for the design of thermal protection system of aircraft.