Abstract: Two lint yield and five fiber quality traits of 9 parents and their 20 F1 crosses (5×4) of sea island cotton in three years were analyzed by the genetic model of additive-dominance and their interactions with environments by MINQUE(1) approaches. The results indicated that there was a negative better-parental heterosis in 5 fiber quality traits, pre-frost lint yield and total yield of F1 and F2 crosses between "0" and long-fruit-branch plant type varieties in sea island cotton. There was a positive low mean heterosis in fiber strength and a negative mean heterosis in Micronaire, but they were low. The positive mean heterosis of F1 and F2 in total lint yield reached 42.1% and 21%, respectively. Generally speaking, the heterosis in fiber quality traits of F1 and F2 was low, but there existed some crosses that their F1 had better-parent heterosis and degenerated F2 heterosis slowly, and crosses have better-parent heterosis in total lint yield of F1 and F2. Pre-frost lint yield could be selected with fiber length or fiber fineness, while it is very difficult to select pre-frost lint yield with fiber strength or there is a difficult to select total lint yield with fiber length, strength, fineness. The phenotypic correlation analysis shows that it is available to use heterosis of pre-frost lint yield with fiber length, strength and fineness synchronously，it is very difficult to use heterosis in total lint yield with fiber length, fineness.

Key words: Sea island cotton, Zero type and "Long-Fruit-Branch" plant type, Yield traits, Quality traits, Heterosis