From July 4 to 11, 2006 at Back Garden site (23°28’86”N; 113°02’91”E), nighttime nitrate radical (NO₃) was measured with a long path differential optical absorption spectroscopy (DOAS) during an intensive field campaign in the Pearl River Delta of China. The NO₃ concentration in polluted air masses varied from 3.6 to 82.5 ppt with an average level of 21.8 ± 1.8 ppt. NO₃ at these levels can play a significant role in oxidation of volatile organic compounds (VOCs). The calculated production rate of nitrate radical ranged from 8 × 10⁵ to 2.98 × 10⁷ cm^-3 s^-1, while its lifetimes spanned from between just several seconds to 650 seconds, with an average of 89 seconds. N₂O₅ levels were calculated with the average of 620 ± 93 ppt during this campaign. The possible scavenging processes for the nitrate radical were obtained by using a statistical analysis of the correlation between NO₃ and NO levels, NO₃ concentration and its production rate, and the NO₃ lifetime and NO₂ levels, respectively. Results showed that the direct losses were of importance at Back Garden in summer Pearl River Delta, China.