Hard clams Mercenaria mercenaria were introduced from America to China in 2000. In this paper, the contents of 18 common acids, protein, fat as well as vitamines and mineral ions in edible part of hard calm were analyzed. The results showed that the contents of 18 common acids and the essential amino acid were 52. 42% and 40. 88% respectively and the average score of essential amino acid was 96. 4 .. 11. 3 according to the FAO/ WHO suggested level ( 1973) , and in which the smelled amino acid takes about 48. 30% . The content of protein in edible part of hard clam was higher( 60. 69% ) and the content of fat was much lower( 5. 60% ) than that of some bivalves. The results also indicated that the edible part of hard clam was also rich in amino acids, vitamins ( A, B1, B2, B5, B6) , and mineral ions such as Ca, Zn, Fe, Mn, etc. Hard clam was suggested to be with higher nutritional value which was good for human health.