This study evaluated the gametic compatibility and zygotic fertility of Crassostrea ariakensis and C. gigas. The fertilization rate, deformity rate and hatching rate at different temperatures (18, 21, 24, 27, and 30 ℃), different salinities (16, 20, 24, 28, and 32) and different sperm concentrations (10⁰, 10¹, 10², 10³ and 10⁴ ind./μL) were compared. The results showed that symmetric fertilization was possible between C. gigas and C. ariakensis, and the zygote could successfully hatch. With the increase of salinity, the fertilization rate and hatcing rate of GG rose, while that of AA and AG rose first and then decreased. GA and AG had better gamete compatibility and zygotic fertility at salinity 28 and 24, in this case, the fertilization rate, deformity rate and hatching rate were 7.45%±5.05%, 2.00%±0.90%, 63.60%±9.88% and 14.26%±9.26%, 1.74%±0.93%, 66.16%±9.43%, respectively. With the increase of temperature, the fertilization rate and hatching rate of AA, GA and GG rose first and then decreased. The fertilization rate, deformity rate and incubation rate of GA and AG at temperature of 27 ℃ were severally 7.95%±4.04%, 1.79%±1.04%, 57.11%±9.95% and 14.70%±7.27%, 1.66%±0.85%, 67.25%±15.19%. With the increase of sperm concentration, the fertilization rate of GG gradually rose and the hatching rate mainly decreased, while the fertilization rate of GA and AG groups gradually increased. The fertilization rate, deformity rate and hatching rate of GA and AG at sperm concentration of 10⁴ ind./μL were severally 9.09%±7.53%, 1.59%±0.48%, 67.97%±19.96% and 14.30%±6.04%, 1.06%±0.68%, 67.33%±12.65%. This study indicate that temperature, salinity and sperm concentration had minor effect on gamete compatibility between C. gigas and C. ariakensis, but had conspicuous effect on zygotic fertility.