To investigate the poisoning effects of the cement dust, the commercial V-based catalyst was directly mixed and aged with the real cement kiln dust. It was found that the introduction of cement dust led to the serious deactivation of catalysts, especially for the aged samples above 300 degrees C. The multiple characterization results (X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, NH3-temperature-programmed desorption, and H-2-temperature-programmed reduction) revealed that the alkaline/alkaline earth metal elements (mainly Ca) can react with the active components through solid phase reaction to form inactive surface A(x)V(1-x)O(4) (A=Ca, K, Na, etc.), solid solutions, and the Scheelite phase, bringing about the reduction of the surface acid sites and the passivation of the redox cycle of V5+/V4+. These results implied that the inert solid solutions may form on the industrial flue gas condition, and change the structure and properties of catalytic sites, which may result in the poisoning and inactivation of the selective catalytic reduction catalyst by cement dust.