Abstract:The 3×3 diallel crosses of different shell color strains were conducted using “Ocean Red”(R),“White”(W) and “Zebra”(Z) in autumn 2006. The experiments consisted of three self-fertilized groups (R R,W W,Z Z) and three hybrid groups (R Z,W Z,W R), in total six reciprocal crosses (RZ,ZR,WZ,ZW,WR,RW). The heterosis of growth, metamorphosis, survival and shell color determinism on offspring were investigated. The results showed that heterosis varied at different phases for each hybrid groups. At pelagic stage, the growth heterosis (Hg=6.20±2.43) increased with post-days and correlativity between the survival heterosis (Hs =14.83±0.28) and post-days was not observed. The hybridized group (W×Z) presented obvious heterosis (Hg w×z =8.50 ±2.79, Hs w×z =20.59±0.98) which was significantly different from those of other group (R×Z、W×R) (P<0.05). At metamorphic stage, the metamorphosis rates of hybrid groups were higher than those of self-fertilized groups and the metamorphic time was was shortened by two days. The metamorphic heterosis was 15.84. At indoor rearing stage, the growth heterosis (Hg =8.98±2.91) was found prior to the survival heterosis (Hs =8.11±8.18). The growth heterosis of hybrid group (W×Z) (Hg w×z =15.93±6.47) was significantly different from that of hybrid group (R×Z、W×R) and the survival heterosis of hybrid group (W×Z) (Hs w×z =8.78±8.76) was remarkably different from (W×R)(P<0.05). At outdoor rearing stage, the heterosis was Hg =12.77±1.20,Hs =49.85±1.93, respectively. The heterosis of hybrid group (W×Z) were Hg w×z =20.92±1.98,Hs w×z =61.60±1.38, the differences of which among hybrid groups were the same as those at juvenile stage. Generally, the heterosis of growth rate were 15.06、17.4、15.77, respectively at larvae stage during larvae stage, juvenile stage and youth stage, juvenile stage and youth stage and no significant difference at each stages was observed. As a whole, the order of heterosis was W×Z>R×Z>W×R. The shell colors of offspring for R×Z, W×Z, W×R were red zebra, white zebra (a posterior band on the left valve) and middle red (a posterior band on the left valve), respectively. The results of both direct cross and reciprocal cross were the same. Results indicated that coloring was not linked to sex and was not of sex-linked inheritance.