Six practical extruded diets were formulated to investigate the effect of graded levels of starch (17, 22, and 26%) associated with either 30 or 34% protein level on growth, feed utilization, body composition, and hepatic transaminases of juvenile grass carp, Ctenopharyngodon idella. Over an 8-wk growth trial, survival rates (99–100%) were not significantly affected (P > 0.05) by dietary treatments. Independent of dietary starch level, weight gain (WG, %), specific growth rate (SGR, %/d), and feed efficiency ratio (FER) showed significant better response (P < 0.05) of fish fed 34% protein diet than those of fish fed 30% protein diet. Protein productive value (PPV) was only affected by dietary protein level, with higher values in the 34% protein level than their 30% counterparts. Irrespective of dietary protein level, lipid productive value (LPV), energy productive value (EPV), viscerosomatic index (VSI, %), intraperitoneal fat ratio (IPF, %), and whole body, liver, and muscle lipid level increased with increasing starch supply. At the same protein level, plasma triacylglycerol (TG), cholesterol (CHO), and low density lipoprotein-cholesterol (LDL-C) increased when dietary starch level increased from 17 to 26%. Neither dietary protein level nor starch level affected activities of hepatic alanine aminotransferase (ALAT) and aspartate transferase (ASAT). The overall results in this study suggested that the higher 34% protein was superior for juvenile grass carp and an increase in dietary starch level did not improve growth or protein utilization but enhanced whole-body lipid deposition and liver, viscera and muscle lipid level. The diet containing 34% protein and 17% starch was optimal for practical production of juvenile grass carp.