The leachate was used to collect the leaching solution from the surface soil of cotton field under different fertilization methods，and the content of total nitrogen，ammonium nitrogen and nitrate nitrogen was measured，so as to study the leaching characteristics of nitrogen in the surface soil of cotton field under different fertilization methods.The site-specific test for 5 consecutive years showed that under the conventional surface irrigation system of cotton field in Xinjiang，the total nitrogen content which leached from the 90 cm soil profiles and the nitrogen loss coefficients were 5.35，5.34，5.52 kg·hm-2·year-1，and 5.49%，4.92%，7.79%，respectively，for there treatments，i.e.farmers’ conventional fertilization，optimized fertilization by soil testing formula，optimized fertilization by soil testing formula plus 50% nitrogen content.Nitrogen leaching was dominated by nitrate nitrogen，accounting for 26.30%~27.85% of the total nitrogen loss，while ammonium nitrogen loss was less，only 2.18%~2.54%.Each irrigation with fertilization will cause nitrogen leaching，but the amount of leaching caused by spring irrigation was 3~5 times higher than other irrigations during the growth period.The nitrogen leaching loss can be reduced by reducing the application amount of nitrogen fertilizer or optimizing the amount of topdressing per time according to the needs of crops.