Hybridization is the most effective thus widely used technique in the artificial breeding of grouper. Salinity is one of the most crucial environmental variables affecting embryonic development in marine fishes. To study the effect of salinity on fertilized eggs of the hybrid grouper () in terms of egg diameter, hatching rate, morphology and survival of the yolk-sac larvae, fertilized eggs were reared in seawater with different salinities, and the effects on total egg diameter, oil globule diameter, hatching rate, abnormality rate, as well as the morphology and survival of the yolk-sac larvae, were observed. The diameter of the fertilized eggs increased with decreases in salinity, whereas the diameter of the oil globule appeared unaffected by the choice of salinity in the test range. Larvae hatched out in the salinity range 18 to 36, but the rates of hatching and abnormalities were significantly affected by salinity level (<0.05). With increases in salinity, the hatching rate first increased at a salinity up to 75.5%, and then decreased at salinity of 30, whereas the rate of abnormalities followed an opposite pattern. The yolk sac was almost completely absorbed within 3 days of hatching at a salinity between 24 and 36, and there was no significant difference between the groups. Within the same salinity range, the survival activity index (SAI) of newly hatched larvae first increased and then decreased with increases in salinity. The newly hatched larvae had an SAI greater than 5; by 5 days after hatching they were starved to death, with half the deaths at 3.5 days after hatching. The fertilized eggs of this hybrid grouper can be hatched out in a salinity range of 24-36, with the optimal salinity at 30-33.