Abstract: The experiment was conducted to investigate the effects of amino acid balanced diets with different protein levels on productive performance, fecal indices and N excretion of lactating sows. Sixty crossbred sows(Large White ? Landrace) sows, with 3-6 parity , similar body condition and parturition dates were selected and randomly divided into 4 groups and each group had 15 sows, and the lactation length was 21 days. Four groups of sows were fed respectively diets with different crude protein(CP) levels 18%( control group), 17%, 16% and 15%, and the latter 3 diets were low CP amino acid balanced diets. The results showed that the productive performance, fecal moisture conten, fecal PH, the quantity of lactobacillus and the quantity of Escherichia coli of lactating sows was not affected negatively (P>0.05), but the N excretion was decreased significantly (PP<0.01), while the reduction of dietary CP was 1% to 3%.