The effects of temperature and salinity on the growth and development of the spats of the clam (Ruditapes philinarum) had been investigated. The results obtained show that. the suitable development temperature range from 15° to 30℃. Tn this range of temperature the spats grow rapidly and the survival rate reaches above 80%，and the optimum temperature is 25℃. The spats show strong tolerance to the low temperature below 20℃ a,nd to the high temperature to 35℃. The lethal critical temperature is about 40℃. The suitable salinity for the growth of spats is about 14 .0-33. 5‰and. 20.5‰ is the optzmum. Within this range the spats develop uniformly with a sure iv al rate ov er 85%.The upper and lower critical salinity for the growth of the spats are shout 7.5‰ and 40‰ respectively. The suitable salinity for metamorphosis of Larvae is in the range of 20.5--33.5‰.The survival rate of holometamorphosis is above 65%.The maximunn rate of holometanzorphosis is more -than 92 .5% in the salinity of 27‰. The lower and upper limits for tine larval metamorphosis era 7，5‰and. 40.0-46 .5‰ respectively.