Abstract: 【 Objective 】 To find out the correlation between dry matter accumulation and nitrogen content of cotton and provide reference for exploring the mechanism of nitrogen transformation.【 Method 】The experiment was conducted to determine the nitrogen content and dry matter of organs in the 4 different varieties.【 Result 】There were some differences in nitrogen content and dry matter accumulation among different cotton varieties, and hybrid cotton had certain growth advantage; Accumulation of nitrogen in each growth stage of cotton varieties in plant nutrition and dry matter accumulation was positively related; Among them, the correlation coefficient of Tian Za No. 2 reached 0.999,8. In the reproductive stage, there was no correlation between the two; Nitrogen content and dry matter accumulation were highest in leaves at bud stage, reaching 7.26 g/hm² and 955.13 kg/hm², respectively; The reproductive organs reached the highest during the late blooming period; Among the different varieties, Tian Za No. 2 was the highest in nitrogen content and dry matter accumulation, reaching 24.64 g/hm² and 11,750.64 kg/hm². 【 Conclusion 】The hybrid cotton has certain advantages in nitrogen and dry matter accumulation, and nitrogen content in vegetative growth stage is linearly related to dry matter accumulation, and leaves occupy an important proportion.