Abstract: Cotton fibers origin from the outermost layer cells of ovule epidermis. The quantity, quality and surface area of cotton seed have effects on cotton lint yield. However, little is known about how within-boll yield components differ between big-boll-weight genotype and small-boll-weight genotype and their relationship of lint yield. Three big-boll-weight genotypes and three small-boll-weight genotypes were field-tested at agricultural experiment station of Jiangxi Agricultural University in 2008 and 2009. Lint yield, yield components and cotton boll characters were evaluated in a randomized completed block design with three replications. The big-boll-weight genotypes had significantly higher lint mass per boll and seed mass per boll than the small-boll-weight genotypes. The seed number per boll of the former was significantly higher than that of the latter. Seed mass per seed did not show any significant differences among those genotypes investigated. Lint mass per seed did not consistently respond to boll weight. It was concluded that the big-boll-weight genotypes in this investigation were characterized by more seeds per boll. The pearson correlation coefficient between seed number per boll and lint yield per hm2 of land area was positive and significant (0.660**), but the partial correlation coefficient was rather small and the direct path coefficient remained negative (0.179, -0.052). The simple correlation, partial correlation and path coefficient analysis revealed that seed number per plant was positively and significantly correlated with lint yield per hm2 of land area. These results indicated that seed number per plant could be served as a reliable character for cotton yield improvement. Lint mass per seed and boll shell ratio were mainly controlled by genetic main effects. Non-significant environmental effects and genotype × environment interaction effects were detected for them.