To improve the oyster phenotypic character,9 Crassostrea gigas families(HH₁₁,HH₁₂,HH₁₃……HH₃₃),9 C.hongkongensis families(GG₁₁,GG₁₂,GG₁₃……GG₃₃)and 45 interspecific hybrid families(C.hongkongensis♀ ×C.gigas〖QX(Y10〗♂〖QX)〗)(HG_{11,HG12,HG13……HG153)were established by the method of unbalanced nest design(one male to three female)in July 2010.Moreover,their early phenotypic character,heterosis potence and heterosis were examined under the identical conditions.These results show that the hybrid weakness of fertilization and hatching levels(hp＜-1)were observed among interspecific hybrid families due to the gametal incompatibility and individual variation.On the whole,the outbreeding depression of larvae growth was observed with the significant hybrid weakness(hp＜-1); the heterosis potence of larval survival ranged from -1 to 1,and survival advantage occurred without the remarkable level; the significantly metamorphic heterosis(hp＞1)was investigated during the planktonic stage.Cytology and molecular biology of interspecific hybridization were further researched on the base of numerous hybrids with genetic information.}