The invention discloses a method for extraction of failure vanadium from a waste SCR catalyst and preparation of activated titanium silicon tungsten powder for making a new denitration catalyst. The method includes: conducting pretreatment on a waste SCR catalyst, performing wet grinding to obtain a slurry, and adding an oxalic acid solution to carry out leaching reaction; carrying out filter-press separation to obtain tungsten silicon-containing titanium slag powder and press filtrate, then performing cleaning, activation, and fine grinding to obtain nanoscale titanium silicon tungsten powder; separating the press filtrate, recovering oxalic acid and returning the recovered oxalic acid to leaching reaction, adding an oxidizing agent into the separated liquid to carry out precipitation reaction so as to obtain ammonium metavanadate precipitate, and conducting filtering and separation to obtain ammonium metavanadate solid. The method provided by the invention uses oxalic acid for reaction under a normal temperature condition, can separate failure vanadium salt from the SCR catalyst, utilizes acid to activate other components and then performs fine grinding and other treatments so as to obtain the raw material for preparation of a new denitration catalyst. The process provided by the invention has the characteristics of low technological investment requirement and low energy consumption, effectively solves the harmless treatment problem of the SCR catalyst, and realizes recycling of resources.