Abstract: The effects of furrow irrigation patterns of i.e. alternative furrow irrigation (AFI), conventional furrow irrigation (CFI) and fixed furrow irrigation(FFI), on cotton nitrogen assimilation and nitrogen use efficiency were studied using field plot experiment．The result showed that cotton biomass, cotton nitrogen content(N), cotton nitrogen absorption rate(NAR), percentage of N derived from fertilizer(Ndff) and nitrogen use efficiency (NUE) in the seeding stage in cotton parts had no significant difference under AFI with that under CFI. However, after buding stage, NUE of stem and leaf under AFI was 9.6% and 18.1% lower than that under CFI, respectively, but NUE of root, buds and bolls had no significant difference. Compared to CFI, N, NAR, Ndff had no significant difference in seedling stage under FFI, However, after buding stage, cotton biomass, N, Ndff, NAR, and NUE was reduced by 22.5%-35.5%, 23.9%-43.8%, 15.0%-39.7%, 35.0%-63.5%, and 34.4%-46.7%, respectively. Our experiment showed that FFI significant reduced the NAR and NUE, but AFI had no influence on them. Therefore, AFI was recommended under the experiment conditions.