The catalysts of V2O5.WO3/TiO2 loaded on ceramic surfaces were investigated to evaluate the behaviors of catalytic activities, sulfur tolerance, K resistance, activities regeneration for K-poisoned catalyst and Si-modification in consideration the catalysts characterization. The results indicated that the high SCR activities of these catalysts correlated with the large acid amount, the absorbed oxygen and the welldispersion of vanadium and tungsten on the surfaces. Washing the K-poisoned catalysts with sulfuric acid could partially recover the catalytic activity because of the K dissolution. Moreover, the incorporation of SiO2 with TiO2 considerably improved the resistance toward potassium because of increasing the acidity of the V2O5-WO3/TiO2 catalyst. The NO conversion increased from 26 to 68% for Kpoisoned VW/TiO2(C-400) catalyst to 76.98% for K.VW/TiO2-SiO2(9)(C-400) catalyst at 260-410 ℃. The NH3 absorption of VW/TiO2-SiO2(6)(C-400) was 236.3 mmol/g, which was much higher than that of VW/TiO2(C-400) (73.3 mmol/g) (approximately 3.2 times higher).