Ammonia (NH₃) slip from denitration (deNO_x) process has been increasingly concerned due to the recent findings that NH₃ played an important role in promoting the formation of haze. Considering the high-temperature and humidity application conditions of diesel exhaust and the location of NH₃-SCO system, Pt/Fe/ZSM-5 catalyst was selected. In this work, Pt-Fe/ZSM-5 catalysts with two different Si/Al ratios (25, 50) were prepared through ion-exchange method and the NH₃-SCO activity were compared both in dry and wet (5% H₂O) circumstances. The Si/Al 25 sample exhibited higher intrinsic activity (dry circumstance) than the Si/Al 50 sample. However, with H₂O addition the activity of Si/Al 25 sample decreased dramatically while Si/Al 50 sample maintained higher level. BET, XRD, XPS, H₂ -TPR, NH₃-TPD and in situ DRIFTS characterization results showed that abundant metallic Pt (Pt°) was beneficial to NH₃-SCO activity, strong acid site determined the water-resisting property of the catalysts during NH₃-SCO with H₂O participation.