A greenhouse pot experiment was conducted in rice-growing season to investigate effect of water management on nitrous oxide (N₂O) emission. Four treatments were established in the experiment:continuous flooding (CF), keeping 3 to 5 cm water layer during the rice-growing season; early aeration (EA), 24 days after rice transplanting; normal aeration (NA), 30 days after rice transplanting; late aeration (LA), 38 days after rice transplanting. The results showed that two peaks of N₂O flux occurred in the mid-season aeration period and 5 to 8 days after re-flooding. The total N₂O emission of different treatments in these periods accounted for 70.30%~94.26% of those emitted in the whole rice-growing season. As far as CF treatment was concerned, N₂O emission accounted for 12.10% of NA treatment. The average N₂O fluxes of EA, NA and LA treatments were 188.56, 158.48 and 147.84 μg/(m²·h), respectively. So it can be easily found that the later soil aeration began, the lower N₂O emitted.