Feeding and nutrition of P.major larvae were studied by diet rducing method and carbon-14 isotopic tagging technique. The resulte shoued thatfeeding rhythemicity of P.major larvae was obviously. The feeding intensity wasstronger in daytime(above 80%)than at night. Two strongest feeding periodswere in the morning and at nightfall.Glucose provided energy for the growth of P. major larvae and wag stored in liver and muscles.Amino acid was one of theimportant substanced for the growth of P.major larvae and there were elevenkinds of essential amino acid for P. major larvae.