The catalytic activity of titania-supported vanadia catalysts was influenced by the state of the active components which were affected by the content of the active components and different calcination temperature. The catalysts were synthesized by sol-gel method and characterized by X-ray Fluorescence Spectroscopy (XRF), X-ray Diffraction (XRD), BET, X-ray Photoelectron Spectroscopy (XPS), Raman Spectra and Transmission Electron Microscopy (TEM). XRD and TEM indicated that quantitative doped active components enhanced thermal stability of the prepared samples and vanadia was well dispersed in the catalyst. BET, XPS and Raman spectroscopy revealed the structure of the catalyst and the state of active components was strongly dependent on vanadia loadings and calcination temperature. These findings were suggested that both vanadia loadings and calcination temperature affect physic and chemical characteristics, resulting in thermal stability and phase composition of the catalyst, higher dispersions and state of active components, ultimately show the catalytic activity of selective reduction reaction for removal of nitrogen oxide by ammonia.