The study was conducted to investigate the effects of four dietary amino acid levels on the productive performance, blood indices and amino acid concentrations in milk of lactating sows based on ideal dietary amino acid pattern. Two hundred Large White×Landrace sows, with similar body conditions and parturition dates, were allocated to four groups with fifty replicates per group and one sow per replicate. The sows were fed with four diets with total lysine levels of 0.9% (trial group 1), 1.0% (trial group 2), 1.1% (trial group 3) and 1.2% (trial group 4) and the same digestible amino acid pattern (digestible lysine∶digestible valine∶digestible threonine∶digestible sulphur amino acids∶digestible tryptophane=100∶85∶66∶60∶19) by adding synthetic amino acids. The results showed that weaning litter weight gain in trial group 2 was higher than that in trial groups 1 and 4 by 4.48% and 4.34% （P<0.01); average daily weight gain in trial group 2 was higher than that in trial groups 1 and 4 by 5.46% and 4.74% （P<0.01). Backfat thickness loss in trial group 2 was higher than that in trial group 4 by 0.57 mm (P<0.05). The concentration of plasma urea nitrogen in trial group 2 was significantly lower than that in the other groups (P<0.05). The concentrations of plasma lysine, threonine, valine, methionine, isoleucine, citrullinde, glutamate, glycine （P<0.01) and leucine (P<0.05) in trial group 2 were significantly lower than those in trial group 4, and there was no significant difference with those in trial groups 1 and 3 (P>0.05) expect that the concentrations of plasma lysine and threonine in trial group 2 were significantly lower than those in trial group 1 (P<0.05). Plasma total amino acids in trial group 2 were the lowest (P<0.05 or P<0.01). The concentration of lysine in milk was significantly lower than that in trial group 4 （P<0.01), but there was no significant difference with trial groups 1 and 3 (P>0.05); the concentrations of valine (P<0.05), isoleucine (P<0.05), leucine (P>0.05), alanine (P>0.05), tyrosine (P>0.05) and glutamate (P>0.05) in milk in trial group 2 were higher than those in the other groups. In conclusion, based on ideal dietary amino acid pattern, when the daily total lysine intake was 59 g/d (1.0% lysine in a diet), the lactating sows could have the highest amino acid utilization and the best productive performance.［Chinese Journal of Animal Nutrition, 2010，22（4）:863-869］