The invention relates to a method for synthesizing 5-(alkylamide-)-9-(N, N-dialkylamide) benzo-phenoselenazine 
hydrochloride shown in a formula I by using nanometer 
copper oxide as a catalyst. A benzo-phenoselenazine derivant, namely the 5-(alkylamide-)-9-(N, N-dialkylamide) benzo-phenoselenazine 
hydrochloride is an excellent 
photosensitizer for a 
photodynamic therapy, has the absorption 
wavelength above 650 nanometers, good water 
solubility, larger absorption intensity, high tumor 
cell selectivity and short metabolic time and is easy for synthesis and 
structure modification, thereby being an ideal novel 
photosensitizer. The method comprises the following steps of: with 3-iodo-N,N-dialkylaniline and 
selenium powder as raw materials, preparing di-(3-N,N-dialkylaniline) 
diselenide shown in a formula II under the 
catalysis of 
copper oxide, carrying out a 
nitrosation reaction on the bi-(3-N,N-dialkylaniline) 
diselenide and 
sodium nitrite to generate a bi-(3-N, N-dialkylamide-6-
nitrosobenzene) 
diselenide, and finally carrying out a cyclization reaction on the bi-(3-N,N-dialkylamide-6-
nitrosobenzene) diselenide and N-
alkyl-1-
naphthylamine to prepare the benzo-phenoselenazine derivant shown in the formula I. The method for synthesizing the benzo-phenoselenazine derivant is mild in 
reaction conditions, simple to operate and high in yield; and the raw materials are available.