Abstract: 【Objective】 To research and explore the secondary growth patterns and occurrence patterns of chemical capping cotton in water and nitrogen operations, optimize the regulation of water fertilizer combined with chemical topping technology, effectively control the secondary growth of cotton, and lay a theoretical and technical foundation for the shaping of cotton plant type and the regulation of harvesting time.【Method】 The test used the Xinluzao 57 as the test material and used the crack zone experimental design. The main area was the nitrogen (pure N) quantity, and three nitrogen (pure N) levels were set: N1, N2, and N3, which were 150, 300, 450 kg/hm², respectively. The sub-area was the amount of irrigation, with 3 irrigation levels: W1, W2, and W3, which were 3,000, 4,500, and 6,000 m³/hm², respectively. The effects of water and nitrogen treatment on agronomic properties, dry matter accumulation, yield and fiber quality before and after secondary growth of chemically topped cotton were studied.【Result】The increase of irrigation water increased the growth period of cotton and increased the plant height, number of fruit branches and secondary growth rate. Nitrogen application controlled dry matter and yield formation factors in cotton. When the irrigation treatment was 4,500 and 6,000 m³/hm², chemical topping cotton plant Gaohe had a high number of branches and was prone to secondary growth. When the amount of nitrogen applied was 300 kg/hm², the yield and composition were higher than others. The combination of water and nitrogen treatment to treat N2W2 and N2W3 performed better, with yields of 6,349.21 and 6,203.54 kg/hm², respectively.【Conclusion】 For chemical topping cotton, proper water and nitrogen operation can control the secondary growth of cotton, and there is no significant effect on the yield and quality of cotton.