Abstract: Using cornstarch wastewater as carbon source for denitrification, the removal effects of nitrate nitrogen and organic matter were studied. The degradation characteristics of dissolved organic matter were investigated by excitation-emission matrix spectrum(EEMs) combined with parallel factor analysis(PARAFAC), and the community structure of microorganisms in activated sludge was analyzed by high-throughput sequencing. The results showed that the removal rate of NO_x^--N(the total concentrations of NO₃^--N and NO ₂^--N) was 96.80%. Two kinds of fluorescence components can be identified by EEMs-PARAFAC, including tyrosine-like substance Component 1(230 nm/310 nm, 275 nm/310 nm) and tryptophan-like substance Component 2(220 nm/350 nm, 280 nm/350 nm). The fluorescence intensity of Component 1 showed a downtrend and disappeared finally, which illustrated that the substance could be completely degraded by microorganisms. The fluorescence intensity of Component 2 gradually increased and Component 2 was the byproduct of microbial metabolism. Three dominant bacteria in the acclimated sludge were uncultured bacterium, Burkholderiales and Rhodocyclales, and the relative abundance of them was 18.54%, 14.65% and 14.13%, respectively.