The validities of Denitrification—Decomposition (DNDC) model and the simulation parameters were examined by using field experiment data obtained from a wheat/maize rotation system. Based on the differences between N availabilities in reclaimed water and inorganic N fertilizer, three scenarios (1∶1, 1.7∶1, 2∶1) were hypothesized to evaluate the feasibility about simulating nitrous oxide (N2O) emission in soil irrigated with reclaimed water by DNDC model. The results showed that DNDC model performed well in verifying the temporal variations of soil moisture under reclaimed water (r=0.716, n=29, P<0.01) and ground water irrigation (r=0.703, n=29, P<0.01), and mean daily temperature (r=0.89, n=35, P<0.01) at soil surface under ground water irrigation. The peaks of N2O induced by irrigation, rainfall and fertilization events were detected by DNDC model. However, the measured N2O fluxes generally lagged behind the simulated fluxes, so the performance of DNDC model were not satisfied in simulating N2O fluxes. The measured and estimated N2O production was 1.84kg/hm2 and 1.83kg/hm2 under scenario 1.7∶1, indicating that N in reclaimed water had higher availability than that in fertilizer, and DNDC performed well for evaluating cumulative N2O emissions on short-term reclaimed water irrigation.