The effects of different proportions of urea and liquid urea formaldehyde slow release nitrogen fertilizer on cotton growth and development，dry matter accumulation，nitrogen accumulation in various organs of cotton，nitrogen use efficiency and yield were studied under different nitrogen levels，so as to provide theoretical basis for high yield nitrogen application management in drip irrigation cotton fields in Xinjiang. Cotton variety “Xinluzao 64” was selected in the experiment，and two nitrogen application methods were set up，namely conventional total urea(T2)and different proportions of urea and slow release nitrogen fertilizer(US). The combined application treatments were set up at three levels according to the nitrogen application rate，namely，no nitrogen reduction of U0.8S0.2(T3)and U0.6S0.4(T4)，nitrogen reduction of 20% U0.6S0.2(T5)and U0.4S0.4(T6)，nitrogen reduction of 40% U0.4S0.2(T7)and U0.2S0.4(T8)，and no nitrogen application(T1)as the control，with a total of eight treatments. The plant height，SPAD value and dry matter accumulation of cotton were measured at seedling stage，bud stage，flowering stage，boll stage and boll opening stage，and the nitrogen accumulation，nitrogen use efficiency and yield per plant were analyzed. The results showed that urea combined with slow release nitrogen fertilizer promoted the growth and yield of cotton. The plant height，SPAD value，dry matter accumulation and yield per plant of T4 treatment reached the maximum without nitrogen reduction. The yield per plant of T4 treatment was significantly increased by 54.09% and 26.50% compared with T1 and T2 treatments，respectively(P<0.05).There was no significant difference in cotton plant height and SPAD value between T5 and T6 under 20% nitrogen reduction，and there was no significant difference in cotton yield per plant and its components between T5 and T6 and conventional total urea T2 treatment. Under the nitrogen reduction of 40%，there was no significant difference in the growth and yield of cotton between T7 and T8 treatments. At the same time，the combined application of urea and slow release nitrogen fertilizer was beneficial to improve the nitrogen absorption and utilization of cotton. The nitrogen agronomic efficiency and nitrogen partial productivity of T4 treatment reached the maximum among the treatments without nitrogen reduction，which were 8.73 and 24.86 kg/kg，respectively. T5，T6 treatments was significantly higher than that of T2 treatment，which were 62.09% and 62.44%，respectively(P<0.05). At the nitrogen reduction level of 40%，the apparent nitrogen utilization rate of T8 treatment with higher proportion of slow release nitrogen fertilizer was 8.51% higher than that of T7. In summary，T4，T5 treatment could significantly increase the nitrogen use efficiency of cotton，which was beneficial to the growth and development of cotton and the improvement of yield per plant，and was the optimal proportion of combined application for high yield and showed high efficiency of cotton in this experiment.