The effects of photosensitizer quinones -2 - sodium anthraquinone (AQS) and 2-methyl-1, 4-naphthoquinone (MQ) on blocking synthesis of nitrosamine were studied by ultraviolet photolysis and compared with the same conditions of ascorbic acid (Vc). The effects of determination conditions such as concentrations, reaction time and ultraviolet radiation wavelengths on blocking nitrosamines by AQS、MQ were investigated. The results show that when reaction time is 1h, quinone concentration is 0.96 mmol/L, ultraviolet radiation wavelengths is 365 nm, their blocking rate could reach the highest value. The blocking capability followed by MQ> AQS> Vc. In the meantime, their cleaning action of nitrite has been determined by spectrophotometer, it has been found that under the same condition, their cleaning ability of nitrite followed by Vc > MQ > AQS.