Abstract: Feeding rates,absorption rates and utilization efficiency of Brachionus plicatilis,Artemiasalina and Platymonas subcordiformis by Penaeus japonicus Bate larvae(M3)were deter-mined with14C-traeer method.Transportation and distribution of glucose and amino acids of artificial diets in Penaeus japonicus were studied with3H-glucose and14C-phenylalanine as the tracers.Experimental results suggested that Brachionus plicatilis was one of the most suitable diets for the growth of Penaeus japonicus at mysis-3 stage. Artemia salina could be used as a supplemental food at denisties of 2-3 individuals/ ml to improve the growth of Penaeus larvae.The unicellular alga, Platymonas subcordiformis,could also be utilized by the mysis-3 stage larvae when provided alone, and the utilization efficiency was about40%.Nutrients were mainly absorbed through mid-gut gland and mid-gut,and then trans ported into tissues and organs by means of blood circulation.Amino acids secm to be activ;in cell metabolism of tissues in Penaeus japonicus,whereas glucose is used as a major source for energy metabolism.