Ethylenediamine (EDA) was added to modified Pt/SiAl catalyst by co-impregnation method for selective catalytic oxidation of ammonia (NH3-SCO), which for the purpose of optimizing the low-temperature ammonia oxidation activity of Pt/SiAl catalyst. The results of several characterizations indicated that the addition of EDA could adjust the states and particle sizes of Pt, and the reduction property of Pt/SiAl catalyst, which together contributed to with the catalytic performance of catalysts and could be confirmed by XRD, TEM, H-2-TPR and COFTIR. Detailed, the result of H-2-TPR revealed more excellent reduction property of Pt/SiAl-E and the CO-adsorption result displayed more electron-rich of Pt species and more Pt-0 species over Pt/SiAl-E than Pt/SiAl. The TEM results demonstrated the average particle sizes of Pt species decreased from 2.8 nm to 2.0 nm after adding EDA. Consequently, Pt/SiAl-E displayed better low-temperature NH3-SCO activity than Pt/SiAl, the light-off temperature of ammonia dropped from 217 degrees C to 205 degrees C.