In this study,effect of different application ratios of base and topdressing nitrogen fertilizer on the nitrogen uptake,the dry matter accumulation and yield of hybrid cotton was explored to provide a theoretical basis for highyield and highefficient cultivation techniques of hybrid cotton in southern Xinjiang.Three treatments with different ratios of base fertilizer to topdressing fertilizer were set up as 0∶10(N1),2∶8(N2)and 4∶6(N3),respectively,and two cultivars of hybrid cotton were used,ie.Zhaofeng1 and Lumianyan30.The result showed that biomass and the nitrogen accumulation increased firstly and then decreased with the reducing of topdressing nitrogen fertilizer rate.The accumulation of dry matter and the uptake of nitrogen of N1 treatment was the least and,the growth period was bring forward and the senescence process was accelerated.In N2 treatment the dry matter accumulation was increased quickly,which increased the biomass accumulation and the amounts of nitrogen accumulation after the appearing flower stage and increased the rate of photosynthetic product accumulation of transferring to the reproductive organs.In N3 treatment,the amounts of the dry matter and nitrogen accumulation of after the flowering stage was reduced,which lessened the allocation proportion of the dry matter and nutrient to the reproductive organs during the blooming stage because of the lower fertilizer proportion of topdressing.The dry matter and nitrogen accumulation were the best when the ratio of base and topdressing fertilizer was 2∶8 in southern Xinjiang,and the boll number and boll weight increased.There was no difference between the two different cotton cultivars.