Abstract: In order to assess the effects of meteorological factors on cotton fiber quality, the field experiments with the materials of Han333 and Lumianyan27 were conducted. The results show that the sensitivities of fiber indexes to meteorological factors are ranged as fiber strength>elongation>micronaire value>2.5% span length. As to the whole growth period of cotton fiber, 2.5% span length and fiber strength as well as elongation are mainly influenced by daily mean minimum temperature, mean relative humidity and daily range of temperature, while micronaire value is mainly influenced by daily mean temperature, effective accumulated temperature above 15℃and mean sunshine hours. Fiber uniformity is mainly influenced by daily minimum temperature at the growth initiation stage, and micronaire value and elongation are influenced by meteorological factors at the elongating stage. There is a significant correlation between fiber quality characteristics and meteorological factors at cotton secondary wall thickening stage. It indicates that meteorological factors of this period are important to fiber quality. At the same time, micronaire value can be also influenced by mean relative humidity at the maturing stage. This study would provide the references for ecological division and ecological model of fiber quality.