Abstract:In this research, 2 generations of CSSLs( Chromosome Segment Substitution Lines) which derived from combination of upland cotton (Gossypium hirsutum L.) CCRI36 (Chinese Cotton Research Institute 36) as the recipient parent and island cotton (Gossypium barbadense L.) hai1 as the donor parent were used to evaluate the phenotype traits related to yield and fiber quality. Compared with recurrent parent in the same year, the variance ranges and genetic variation coefficients of all traits in populations were very large. In 1942 BC5F3 individuals, the largest lint percentage was up to 49.57%, and the lint percentage was 71.78% higher than recurrent parent, the peak value of fiber strength reached 36.5cN/tex. In 658 BC5F3:4, the maximum value of fiber length and fiber strength reached 32.25mm and 32.2cN/tex respectively, the transgressive rates were 47.57% and 40.27% for fiber length and fiber strength. The correlation analysis showed that it was positive correlation for yield and fiber quality traits between the two generations, but the negative correlation between fiber quality and lint percentage still existed. These results indicated that there were abundant genetic variations and individuals with good yield and fiber quality in CSSLs, the materials were stable and consistent in two generations. However, it was still difficult to improve fiber quality and lint percentage simultaneously. In this study, many materials were provided, which could be further used for QTL fine mapping, gene cloning and molecular assistant pyramid breeding.