For the purpose to select suitable food for cultivation of the larvan of Ruditapesphilippinarum,a series of comparative experiments had been carried out. Several speci-es of unicellullar algae were selected for test, and the results obtained were as follows: 1. Food should be given at the stage of veliger. At this stage, the larvae showed apreferable selection for the size and activity of the feeding algae. If the small-sizedand highly multiplicative unicellullar algae could be provided in time, the period ofcultivation of the larvae might be shortened. 2. Six species of unicellullar algae were used in the tests. The result showed thatDicrateria zhanjiangensis, Cheatoceros sp., Cheatoceros simplex and Phaeodactylumtricornutum were found to be better. Survival rate could reach to 36-50%. When fedwith Heterogloea sp. growth apeed and survival rate of the developing larva were verylow. The big size and the strong activity of Platymonas sp. could hardly be graspedby the larvae. 3. If the larvae were fed with mixed food of Dicrateria zhanjiangensis andCheatoceros sp., or Dicrateria zhanjiangensis and Phaeodactylum tricornutum, the deve-lopment of the larvae and the survival rate raised to 70-71%. 4. The feeding quantity is also important in the cultivation of the larvae. Experi-ments showed that at begining the quantity should be controlled at 15000 ind./ml. perday, two days later it should be gradually raised to 40000-50000 ind./ml. per day. 5. By feeding with senescent algae, there was evident effect on the growth andmetamorphosis of the larvae. Aged Cheatoceros sp. gave no evident effect, but agedDicrateria zhanjiangensis had evident effect on the larvae and varying with the degreeof senescense.