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In order to reveal the residue of fertilizer nitrogen in paddy soil under the watersaving irrigation model in the low temperature black soil area of Songnen Plain, two irrigation modes were set up in the field experiment, which were controlled irrigation and conventional flooding, and three nitrogen levels (85kg/hm2, 110kg/hm2 and 135kg/hm2) and six treatments. At the same time, by using the method of 15N tracer in situ in the field plot, the basal, tillering and panicle nitrogen fertilizers were labeled and treated with a total of 18 parts. The residue of fertilizer nitrogen in paddy soil after rice harvest was studied, and the distribution of fertilizer nitrogen in 0~60cm soil in paddy field was investigated. The results showed that the residual rate of basal nitrogen in paddy soil was 29.7%~32.7% under different nitrogen levels, and the residue rate of tillering fertilizer was 54.9%~57.3%, and the residue rate of panicle was 29.4%~35.4%; the total residue rate of fertilizer nitrogen in soil was 36.4%~37.1%, the residual rate of the fertilizer nitrogen in the soil was higher than that of the conventional flooding irrigation under the same nitrogen application. There were significant differences in the residues of fertilizer nitrogen in the same depth soil under different irrigation modes. Under different nitrogen application conditions, the residue in rice paddy soil (0~20cm) was higher than that in the normal flooded irrigation mode during the growth period of paddyfield. The residual amount of 20~40cm and 40~60cm soil was lower than that of conventional flooded irrigation. Compared with the conventional flooding irrigation, the riceirrigated model can improve the residue of fertilizer nitrogen in root soil (0~20cm), and reduce the loss of fertilizer nitrogen, and the residual fertilizer nitrogen can supplement the soil nitrogen reservoir in the black soil area to some extent. It was beneficial to soil protection and fertility improvement of paddy field in black soil area. The correlation analysis showed that the total residue of fertilizer nitrogen in soil was positively correlated with the residue of fertilizer nitrogen in soil, and the residue of basal and spike fertilizer was significantly positive. The research results provided a reference for the formulation of suitable water and nitrogen regulation model in the black soil region, effectively managed and made full use of residual nitrogen fertilizer, and improved the paddy field ecological environment in black soil area.