Freshwater scarcity is a serious long-term hindrance to the agricultural production in arid and semi-arid regions. While the supply of brackish water is quite plenty, therefore the use of brackish water or saline water for irrigation has received considerable attention in those regions. A field experiment was carried out to study the effect of drip irrigation with saline or brackish water in cotton (Gossypium hirsutum L.) fields on fate of nitrogen in the soil relative to salinity of the water, irrigation rate, and N application rate. ¹⁵N-labeled urea was applied in the experiment field or plots to trace N movement in the soil. The experiment was designed to have three treatments (S_0.35, S_4.61, and S_8.04) in salinity of irrigation water (0.35, 4.61, and 8.14 dS m^-1, respectively), two levels in irrigation rate (405 mm and 540 mm), and two levels in N application rate (240 and 360 kg hm^-2, 360 kg hm^-2 is a common rate used by local farmers). The experiment shows that both cotton yield and N uptake were significantly lower in Treatment S_8.04 than those in Treatment S_0.35 and S_4.61, and there was no significant difference in either cotton yield or N uptake between Treatment S_0.35 and Treatment S_4.61. Salinity of the water affected mainly the number of cotton bolls and hence yields of the crop. Cotton yield and N uptake increased with irrigation rate and N application rate. Results of ¹⁵N tracing show that the plant 15N recovery rate ranged from 34.20% to 62.51%, and followed a curve that rose first and then declined with rising salinity of the water. Plant ¹⁵N recovery rate in Treatment S_4.61 was 30.70% higher than that in Treatment S_0.35 and 41.77% higher than that in Treatment S_8.04. Higher irrigation rate or N application rate significantly increased plant ¹⁵N recovery rate, however, higher salinity of the irrigation water decreased that. Treatment S_8.04 and Treatment S_8.04was 4.03% and 23.88% higher, respectively, than Treatment S_0.35 in soil ¹⁵N residue rate. Increase in N application rate from 240 kg hm^-2 to 360 kg hm^-2increased soil ¹⁵N residue rate by 9.51%. Total ¹⁵N recovery rate was significant higher in Treatment S_4.61than in Treatment S_0.35and Treatment S_8.04 ¹⁵N leaching rate in the treatments ranged from 0.35%~3.59%, depending on treatment and was significantly affected by salinity of the irrigation water. When N application rate was low (240 kg hm^-2), ¹⁵N leaching rate did not differ much between Treatment S0.35 and Treatment S_8.04, but the rate in Treatment S_8.04 was 187% higher than that in Treatment S_0.35 and 84% higher than that in Treatment S_4.61. When N application rate was high (360 kg hm^-2), ¹⁵N leaching rate increased significantly with salinity of the irrigation water, irrigation rate, and N application rate increased. The above-listed findings suggest that the use of brackish water in drip irrigation, if salinity of the water, irrigation rate and N application rate are all controlled to a proper level, would not affect growth, yield and N recovery of the cotton crop. But if the water is too high in salinity it would inhibit cotton growth and lower cotton yield and nitrogen use efficiency as well. In this experiment, 60.22% to 86.70% of the N fertilizer applied was recovered by the crop, 0.35% to 3.59% lost through leaching and the remaining 12%~38% through ammonia volatilization, nitrification and denitrification. Therefore, a suitable “water-salt-fertilizer” management helps improve nitrogen fertilizer utilization efficiency and reduce N loss.