The present experiment was conducted to explore the effects of supplementation of crystalline or micro-capsulated amino acids in low fish meal diet on growth performance of common carp (Cyprinus carpio）. Four diets were prepared, which were high fish meal （FM） diet with 15% FM in prophase (1 to 28 d) and 10% FM in anaphase (29 to 56 d), low FM diet with 10% FM in prophase and 5% FM in anaphase, low FM diet added with crystalline lysine and methionine, and low FM diet added with micro-capsulated lysine and methionine. The later two diets of each stage had the same lysine and methionine levels as the high FM diet. Common carp (5.0±0.5) g were fed the four diets with triplicate for 8 weeks. Four hundred and eighty healthy common carp with an initial body weight of (5.3±0.5) g were randomly assigned to 4 groups (with 3 replicates of 40 fish) and fish in each group were fed 1 experimental diet. The results were as follows: compared with the low FM group, supplementation of crystalline amino acids had no significant effect on growth performance (P>0.05), but the weight growth rate (WGR) was improved by 8.67% and feed conversion ratio (FCR) was decreased by 7.46% (P<0.05) by adding micro-capsulated amino acids in diet. The growth performance of micro-capsulated amino acid group was similar to that of the high FM group (P>0.05). Plasma total free amino acid (TFAA) content at 0, 1, 2, 3, 4, 5 h after feeding was determined, and the highest content of TFAA occurred at 3 h after feeding high FM diet, and low FM diet added without or with micro-capsulated amino acids, but absorbing peak occurred at 2 h after feeding low FM diet added with crystalline amino acids, which meant the absorbing peak was advanced. Dissolve-loss rates of crystalline lysine and methionine were significantly decreased by micro-capsulating, respectively (P<0.05), and the dissolve-loss rates of micro-capsulated lysine and methionine were equal to only 28.4% and 4.9% of the dissolve-loss rates of crystalline lysine and methionine, respectively. It is concluded that supplementation of micro-capsulated amino acids in low FM practical diet of common carp can improve WGR, and decrease FCR, but supplementation of crystalline amino acids in low FM practical diet of common carp can not affect the growth performance.［Chinese Journal of Animal Nutrition, 2010，22（6）:1599-1606］