A study of food and feeding habits of spats and larva of the clam (Ruditapesphilippinarum) was carried out by feeding with planktonic and benthic uni-cellularalage. Results of the experiment are as follows:1. The spare feeding on unicellular algae used in the experiment grew normally.Among them, those feeding on mixed food of benthic diatom and Chaetocerous sp. grewfaster (33.7 micron per day) with higher suvrival rate (ca. 80%) than-the spatsfeeding on other kinds of food.Another mixed food of Dicxateria zhanjingensis and Chaetoceros sp.also gaveideal results with spat growth rate of 29.2 micron per day and survival rate about80%.2. The density of food organism is an importat factor to the growth of spats.Experments show a food density of 25,000--50,000 individuals per millilitre is com-paratively suitable for culturing of spats no matter the food is single or mixed.3. Platymonas sp. is very active whan lives and is not easy for the bottom-livingspats to catch. So, that frozen and heated Platymonus sp. were used in our experi-ment. The results show frozen Platymonus gave better result.4. Although suitable food might increase the survival rate of spats of the clam,yet there are another factors affecting its survival rate such as temperature and salin-ity and the effects of bottom soil should also be considered.