Abstract: The effects of irrigation frequency, irrigation amount, as well as nitrogen application rate on the growth, yield, and water use efficiency（WUE） of cotton under mulched drip irrigation were stu-died. The optimal mode of irrigation and its frequency, as well as nitrogen application were explored to provide the scientific basis for water and nitrogen management of cotton under mulched drip irrigation. The experiment was conducted in three irrigation time intervals of 7 days（D1）, 10 days（D2） and 13 days（D3）. Two irrigation quotas of 4 400 m~3/hm~2（W1） and 3 300 m~3/hm~2（W2）, as well as two nitrogen application levels of 300 kg/hm~2（F1） and 225 kg/hm~2（F2） were set in the experiment. Each treatment was repeated 3 times and a total of 12 treatments were conducted. The results show that the plant height of D1 is 2.90% and 7.96% lower than that of D2 and D3, respectively. The leaf area index positively correlates with the irrigation frequency, the leaf area index of D1 is 1.96% and 7.28% higher than that of D2 and D3, respectively. The ratio of bud and boll biomass to above-ground biomass increases with the increase of irrigation frequency.The yield of D1 increases by 3.84% and 11.76% compared with D2 and D3, respectively. The yield of W1 increases by 5.56% compared with W2, and the yield of F1 increases by 13.49% compared with F2. The WUE of D1 is 2.75% and 9.80% higher than that of D2 and D3, respectively, and the WUE of W2 is 22.71% higher than that of W1. The WUE of F1 is 11.37% higher than that of F2. These results indicate that D1 level avoids excessive growth of cotton, improves the development of the cotton population, enhances the photosynthesis and material production capacity of the population, ensures the reproductive growth of above-ground biomass, as well as increases irrigation quota and nitrogen application. The plant height, leaf area index, and above-ground biomass of cotton also increase significantly, thus increasing the cotton yield. In addition, high-frequency water reduction can maintain the appropriate degree of root water and meet the water demand of cotton. High nitrogen can meet the nitrogen demand of cotton growth, reduce water evaporation loss, and improve water use efficiency. Therefore, considering the cotton yield and water use efficiency, it is concluded that the irrigation frequency is 7 days, the irrigation quota is 3 300 m~3/hm~2, and the nitrogen application rate is 300 kg/hm~2 in this study.