Abstract: [Objective] This experiment aims to explore the cotton boll development and the effect on fiber quality and yield of Xinluzao cotton varieties,which might be of great significance to construct high-yielding cultivation technique system and new variety cotton breeding in Xinjiang.[Method] Field experiments were carried out to study the characteristics of cotton boll development among 12 main cotton varieties used widely from 1980s to 2010s,and the boll length,diameter,volume,single boll weight,yield and fiber quality during development were determined.[Result] During the evolutional succession of Xinluzao cotton varieties,boll length,boll diameter,boll volume and boll weight decreased by 2.79;-16.92;,2.27;-13.28;,10.15;-35.9; and 11.5;-18.9;,respectively;Bolls number per plant and seed cotton yield increased by 4.0;-45.29; and 8.75;-28.04;,respectively.From 1980s to 2000s,fiber length and fiber strength increased;during the period from 2000 to 2010,there were no obvious changes.The correlation analysis showed that boll length,boll diameter and boll volume were significantly negatively correlated with the bolls number per plant,seed cotton yield,fiber uniformity and micronaire,and significantly positively correlated with single boll weight,fiber length and specific strength.The further path coefficient analysis showed that boll length and boll diameter went against increasing bolls number per plant,but both helped to improve fiber strength and fiber length.[Conclusion] The increase of yield was mainly attributed to the increase of boll number per plant during the evolutional succession of Xinluzao cotton cultivars,and the length and diameter of 0 ～21 d were closely related to the yield and quality.