Abstract: Hybridization and back crossing between Crassostrea hongkongensis and Crassostrea ariakensis were conducted in this study, consequently, the experimental groups HH (C. hongkongensis), AA (C. ariakensis), HA (C. hongkongensis ♀× C. ariakensis ♂), AH (C. hongkongensis♂× C. ariakensis♀), HAHA (HA♀×HA♂), HHA (HH♀×HA♂), HAH (HA♀×HH♂), HAA (HA♀×AA♂), AHA (AH♀×AA♂) were produced using the method of diallel cross. The results showed that C. hongkongensis eggs can be fertilized by C. ariakensis sperm (47.33±2.52%), but not vice-versa. The fertilization can be occurred between HA and HH or AA. The fertilization rates of backcrossing groups were lower than inbred groups HH and AA. The hatching rate of the back crossing between HA and AA were lower than the other groups, which were 20.33±2.08%(AHA),55.67±2.52%(HAA)respectively. The larval survival rate of the AHA and HAHA were 0; The survival of HA larvae was lower than HH and AA. The hybrid larvae grew faster than C.ariakensis larvae, but grew slower than C.hongkongensis. The survival rate of HA, HH, and AA juveniles was not significant difference(P>0.05). The hybrid juveniles grew faster than C.hongkongensis larvae, but grew slower than C.ariakensis. In addition, the larval and juvenile growth of HHA and HA was not significant difference(P>0.05). The larval survival rate was not significant difference in HHA and HA. The juvenile survival rate of HHA was lower than HA, but was higher than that of the other backcrossing groups. The results provide the basic study on the hybridization and backcrossing between C. hongkongensis and C.ariakenis.