Abstract: An experiment shows that nitrate can be reduced to nitrite by spongiform zinc-cadmium reducer. Based on the experimental resul,t the chemiluminescence of hydrogen dioxide and luminol solutionwas used to the on-line analysis ofnitrite and nitrate. As a resul,t a new chemiluminescence method for the simultaneous determination of nitrite and nitrate was proposed. The system responds linearly in the range of3×10-3~3 mg/L for nitrite and 1~100 mg/L for nitrate, and the detection limits fornitrite and nitrate are 1. 5×10-3and 0. 33mg/L respectively. Thismethod hasbeen used to determine nitrite and nitrate in environmental water samples. The result shows that the maximum relative standard deviation is less than 4%.