This study was to investigate the effect on the conversion, long-term test, product selectivity and kinetics in oxidation of ammonia over copper catalyst supported on slag powder. The operation parameters in heterogeneous reactor were performed as follows: 1000 ppm initial concentration of ammonia, temperature of reaction in ranging from 100 ¢J to 500 ¢J, 10 % of oxygen concentration, and 80000hr-1 of space velocity. In the experiments of catalyst selection, we decided to use 15% Cu catalyst for its high conversion and selectivity in oxidation of ammonia. The conversion of ammonia in catalytic reaction increased with the increasing both of reaction temperature and influent concentration of oxygen but decreased with the going up of initial concentration of ammonia and of space velocity. In the long-term test of catalyst stability, Cu catalyst had a good stability after 48 hours reaction in heterogeneous reactor. The tests such as XRD, SEM and EA were also determined. The kinetics of heterogeneous reactor over Cu catalyst supported on slag powder in oxidation of ammonia was found that a pseudo-first order could be described by Mars-Van Krevelend model. The apparent reaction order and activated energy were obtained.