The effects of temperature, salinity, pH, egg density, chemical fertilizer and phytoplankton on the hatching rate of eggs of Sinonovacula constricta have been studied. It is found that the suitable temperature is in the range of 20-25℃ and pH7.0-8.5. The suitable salinity varies with diffrent sources of razor clam; optimum salinity is in the range of 8-12% for low salinity areas and 15-30% for high salinity areas. Temperature has effect on the range of suitable salinity and the range at 25℃ is the widest.Th...