The nitrogen loss in farmland was one of the main reasons which led to agricultural non-point source pollution. The excessive nitrogen application rate and irrigation quota were two significant factors which led to the nitrogen loss in farmland. This research would be helpful to figure out the temporal-spatial distribution features of NO3--N in leaching water and the influence of two factors on NO3--N leaching loss with different water and nitrogen management patterns. Then made a safe and effective water-nitrogen management pattern. The experiment used a completely random split plot design method. The main plot was irrigation quota with three levels (W1: 525 m3/hm2

W2: 750 m3/hm2

W3: 975 m3/hm2). The split plot was nitrogen application with five levels (N0: 0 kg/hm2

N1: 80 kg/hm2

N2: 160 kg/hm2

N3: 240 kg/hm2

N4: 320 kg/hm2). Every irrigation quota had five treatments with different nitrogen application rate. There were fifteen treatments in total. The field experiment was carried out in 2014

2015. Adopted the methods of porous PVC and soil auger to collect water and soil samples. Measured the concentration of NO3--N in leaching water and calculated the leaching loss of NO3--N. With the increase of nitrogen application

the two years’ average increase of NO3--N concentration by W1 was far below the two years’ average increase of NO3--N concentration by W2 and W3 within the soil depth of 0—40 cm. With the increase of irrigation quota

the average increase of NO3--N concentration by N1 and N2 were far below the average increase of NO3--N concentration by N3 and N4 within the soil depth of 0—40 cm. The largest average increase of NO3--N concentration was 52.5% which belonged to W3N3. The highest average concentration was 8.29 mg/L which belonged to W3N4. Compared with the treatments in 0—40 cm soil depth

the NO3--N concentration of treatments showed the overall declination within the soil depth of 40—80 cm. But the change trend of NO3--N concentration was consistent with the soil depth of 0—40 cm. Within the soil depth of 80—120 cm

the leaching loss of NO3--N was significantly influenced by the nitrogen application

irrigation quota

and the interaction of those two elements. When the irrigation quota was constant

the NO3--N leaching loss of 2014

2015 would increase with the increase of nitrogen application. The NO3--N leaching rate of 2014

2015 would decrease with the increase of nitrogen application. When the nitrogen application was constant

the NO3--N leaching loss and NO3--N leaching rate of 2014

2015 would increase with the increase of irrigation quota. The crop needed sufficient NO3--N to absorb in root layer. The pollution of NO3--N leaching loss on the groundwater should be controlled in the safety range. Considering the two aspects above

this research recommended the W2N3 as the best water-nitrogen management pattern for experimental region.