Abstract: The biological characters，morphology，density and structure of pubescence of a new cotton species named heterotetraploid Gossypium arboreum bickiiA₂A₂G_lG₁are studied in this paper．The results indicate that the pubescence of stem and leave are mainlv distributed on the vein,and the densities of the pubescence show a decreasing tendency frommiddle vein．side vein to branch vein．Moreover．pubescences on stem are more than those on leaves，those on 1eaves are more than those on flower apparatus，the average density on stem is 12．30 per mm²，and that on leaves is 10．38 per mm²；the pubescences include mono-pubescence and multi-pubescence．The amount of multi-pubescences is more than that of mono-pubescences．Generally，there are 6～7 pubescences per multi-pubescence，even more than 15．The length of pubes-cence is up to 620um ．The longer pubescence in stem and leavcs，as the excellent trait of anti-insect，is inherited and expressed from the wild G bickii as a father of G arboreu11l bickii．