Abstract: 【 Objective 】 To understand the characteristics of cotton boll development in the main land cotton in this area. 【 Methods 】 Xinluzhong 82, Xinluzhong 70 and strains 15-1242 were used as materials, and flowers were hanged on July 7, July 14, and July 21, respectively, every 7 days.【 Results 】 The test showed that the dry weight of cotton bolls was 15-1242>Xinluzhong 70>Xinluzhong 82,7>14>21. The rapid growth stop time of the three bell-type indicators was significantly positively correlated with the dry weight of the single bell; the length of the bell had the greatest influence on the dry weight of the single bell, followed by the volume and diameter of the boll; the length of the boll played a direct role in the increase of the volume. And the diameter affectedthe volume increase by indirect action. The dry matter accumulation and distribution of the cotton bolls of the three materials showed that the fastest decrease in the shell rate was 65% to 20%, and the fastest increase in the fiber rate and seed rate was Xinluzhong 70,from 17% to 37% and 16 to 41%, respectively. The dry matter accumulation characteristic curve of each component of cotton bolls showedthat the bell shell requiredthe shortest time, the seed was centered, and the fiber was the longest. During the vigorous accumulation of cotton bolls, the normal development of seeds and fibers was critical to the formation of cotton single boll weight, which directly affectedthe final yield of cotton. 【 Conclusion 】 The single boll weight, volume and dry matter accumulation distribution of Xinluzhong 70 were the best in the three materials.