An experiment was organized to study the effects of the combined application of nitrogen and boron on the yield,petiole annulus and nutrient uptake of cotton.The results showed that nitrogen and boron fertilizers had some interaction on cotton.At the same application of nitrogen,the ratio of cotton petiole annulus,the number of leaves with petiole annulus per plant and the petiole annulus of each leaf were significantly reduced with increasing boron application.When increasing the boron from 0 to 13.5 kg/hm2,the nitrogen,phosphorus,boron and chlorophyll content of cotton leaves increased,the plant height,branch,bolls per plant,boll weight,lint percentage rate of cotton and yield were significantly increased.when the boron application was from 13.5 to 27 kg/hm2,the phosphorus,potassium,boron and chlorophyll content of cotton leaves had no significantly change under both nitrogen levels.At the application of 270 kg/hm2 nitrogen,the nitrogen content of cotton,the plant height,boll weight and the bolls per plant were decreased,while the yield had no significant change.When the application of nitrogen was 375 kg/hm2,the nitrogen content of cotton,bolls,boll weight,lint percentage rate of cotton and yield was significantly increased.At the same application of boron,with nitrogen increasing,the ratio of cotton petiole annulus,the number of leaves with petiole annulus per plant,the petiole annulus of each leaf,the nitrogen and chlorophyll content of cotton leaves were significantly increased,but it had no significant effect on the phosphorus,potassium,boron and chlorophyll content of cotton leaves.The highest yield was 3 592 kg/hm2 at N 270 kg/hm2 and B 13.5 kg/hm2.It showed that increasing boron and reducing nitrogen inputs effectively relieved boron deficiency of cotton in Tianmen city,Hubei provinc