The chief chemical composition of some marine zooplanktonic crustaceans, Acetes, chin-ensis,Euphausia sp, Acanthomysis longirostris and Copepods-mainly Schmakeria poplesia, offAmoy water and its vicinity has been analysed, with special emphasis laid on the proteinand the essential amino-acids contents. The results reported in this paper show that theprotein content of these animals is quite rich, amounting to 50% or over in the dry matterbase and the essential amino acids of the protein are fairly complete. Among the animalspecies analyzed,the copepod is especially prominent in these respects and contains essentialamino acids in higher proportion than the other species. When prepared dry, both the con-tents of protein and the proportion of essential amino acids are without much lost. The content of the lipid in the zooplankton is higher than that in the benthos, but thereverse is true of the ash. The results show that the marine zooplanktonic crustaceans have a relatively high nut-ritive value as the food for human consumption as well as for the marine economic animals,and, therefore are of great importance to the fisheries.