Ta and N co-doped SrTiO 3 was synthesized by microwave-assisted solvothermal reaction using SrCl 2 ·6H 2 O, Ti(OC 3 H 7 ) 4 , TaCl 5 , and HMT (hexamethylenetetramine) in KOH and oleic acid mixed solutions. The products were characterized by XRD, TG-DTA, BET surface area measurement, TEM, EDX, DRS, PL-Spectra, and XPS. The nanoparticles of perovskite-type SrTi 1−x Ta x O 3−y N y (x = 0 − 0.1) were successfully synthesized. The photocatalytic activity of SrTiO 3 for DeNO x ability in the visible light region could be improved by the codoping of Ta 5+ and N 3− . The excellent visible light photocatalytic activity of this substance may be due to the generation of a new band gap by doping nitrogen that enables the absorption of visible light as well as a decrease in the incidence of the lattice defects, which acts as a recombination center of photo-induced electrons and holes by codoping with Ta 5+