Two novel iV-heterocycle-containing benzotriazole compounds,5-(5-chloro-2-benzotriazolyl)-6-hydroxy-l,4-dimethyl-3-car-bonitrile -2-pyridone(2) and 4-(5-chloro-2-benzotriazoIyl)-5-methyl-2-phenyl-3-pyrazolone(4),were synthesized from reactant 4- chloro-2-nitroaniline via diazotization,azo coupling,reductive cyclization and acidification.Their structures were confirmed by FT-IR,~1H NMR,mass spectroscopy and elemental analysis.Their spectral properties were investigated and compared with that of a common commercial benzotriazole UV absorber Tinuvin 326.It is found that the novel Af-heterocycle-containing benzotriazole compounds exhibit sharp single peak in the range of 280-400 nm and have much higher molar extinction coefficients than that of Tinuvin 326.Their anti-UV protection properties on polyester fabric were also evaluated and compound 4 was much superior to compound 2 due to its higher exhaustion. Two novel iV-heterocycle-containing benzotriazole compounds, 5- (5-chloro-2-benzotriazolyl) -6-hydroxy- chloro-2-benzotriazoIyl) -5-methyl-2-phenyl-3-pyrazolone (4) were synthesized from reactant 4-chloro-2- nitroaniline via diazotization, azo coupling, reductive cyclization and acidification.Their structures were confirmed by FT IR, ~ 1H NMR, mass spectroscopy and elemental analysis. The spectral properties were investigated and compared with that of a common commercial benzotriazole UV absorber. Tinuvin 326.It was found that the novel Af-heterocycle-containing benzotriazole compounds exhibit sharp single peak in the range of 280-400 nm and have much higher molar extinction coefficients than that of Tinuvin 326. Their anti-UV protection properties on polyester fabric also also and compound 4 was much superior to compound 2 due to its higher exhaustion.