Machine-harvested cotton planting has become the main cultivation mode of cotton in Xinjiang. Due to the change of planting density and drip irrigation system，it is urgent to study the effect of nitrogen on machine-picked cotton in order to scientifically and rationally guide the application of nitrogen fertilizer. Field experiment was used in this study. Under the same nutrient input ratio (N∶P2O5∶K2O= 1∶0.38∶0.3)，different nitrogen fertilizer application rates (0，180，220，270 and315 kg/hm²) were set up to study the effects of nitrogen on nutrient uptake and utilization of cotton plants，fertilizer utilization rate，soil nutrient changes and yield of cotton fields in Northern Xinjiang. The results showed that the boll number per plant and the seed cotton yield were increased with the increase of nitrogen application rate，and the boll number per plant was significantly increased thereby the seed cotton yield，but the nitrogen application had no significant effect on the cotton lint percentage. Aboveground dry matter weight and plant nutrient uptake were positively related to nitrogen application. 100 kg seed cotton needed nitrogen 5.10 kg，phosphorus 1.37 kg and potassium 4.90 kg. The accumulation of nitrogen and phosphorus in seed cotton was higher than that in straw，but the accumulation of potassium was the opposite. The soil nutrient content in the surface layer (0-20 cm) was the most affected by the application of nitrogen fertilizer. The harvest index and fertilizer utilization rate of cotton with 270 kg/hm² of nitrogen application were the best，and the nutrient balance could be reached. Considering yield，fertilizer utilization rate and nutrient balance of cotton field，it is suggested that the optimal nitrogen fertilizer amount for machine-harvested cotton by drip irrigation under film in Northern Xinjiang is 270 kg/hm².