Abstract: The effects of pH on the hatching of Coelomactra antiquata fertilized eggs and on the development as well as attachment metamorphosis of velige larva were studied. The results showed that the optimal pH for fertilized eggs to be hatched to trochophore larva was 7.0~8.5, while the optimal pH for trochophore larva to grow to straight line hinge larva was 7.5~8.5. Velige grew faster when pH was 8.0~8.2 and the average daily growth gain of shell length was 15.0~16.5 μm on average. When water temperature was 26.4±0.45 ℃, salinity 25.50 and pH 8.0~8.2, C.antiquata veliger with an average shell length of 196 μm, after 72 hours of cultivation, reached attachment metamorphosis at a rate of 51.66%~53.00%.