The invention discloses a method for preparing alpha-azidoketone compounds based on photocatalysis. The method is based on a reaction formula shown in the description, wherein R<1> is optionally-substituted aryl, heteroaryl or 1-12 carbon alkyl; R<2> is optionally-substituted aryl, heteroaryl or 1-12 carbon alkyl, or a hydrogen atom. One substance represented by a general formula I is set as one olefin, a substance represented by a general formula II is set as azidotrimethylsilane (TMSN3), and one substance represented by a general formula III is set as one alpha-azidoketone compound, one alpha-azidoketone compound is synthesized under visible light catalysis. According to the method disclosed by the invention, a photocatalyst is designed, one alpha-azidoketone compound is synthesized by adopting air as an oxidant under the visible light catalysis, an equivalent-weight inorganic oxidant, metal reagent and pre-prepared complex raw material are not used, so that the reaction conditions are reduced, and the reaction safety is improved.