Effects of supplementation of lysine on digestion and metabolism of lambs was studied. Sixteen male Small Tail Han sheep lambs with the age of 60 to 85 days in experiment 1 and 120 to 145 days in experiment 2 were divided into 4 groups (4 replicates per group, and 1 lamb per replicate), and the basal diets were supplemented with lysine of 0, 0.6%, 1.2% and 1.8% in experiment 1, and 0, 0.2%, 0.4% and 0.6% in experiment 2, respectively. The results showed as follows: in experiment 1, compared with the control group, the 0.6%, 1.2% and 1.8% supplementation of lysine increased the digestion amount of organic matter (OM) by 8.55% (P<0.01), 10.36% (P<0.01) and 4.21% (P>0.05) and 20.03% (P<0.05), respectively; increased nitrogen retention (NR) by 12.04% (P＞0.05), 35.85% (P＜0.05), respectively; and increased daily weight gain (DWG) of lambs by 12.08% (P＜0.01), 35.88% (P＜0.01) and 19.98% (P＞0.05), respectively; 2) in experiment 2, compared with the control group, the 0.2%, 0.4% and 0.6% supplementation of lysine increased the digestion amount of OM by 2.64% (P＞0.05), 16.77% (P<0.01) and 6.33% (P＞0.05), respectively; increased NR by 18.14% (P＜0.05), 32.80% (P＜0.05) and 19.75% (P＜0.05), respectively; and increased DWG of lambs by 18.17% (P＜0.01), 32.73% (P＜0.01) and 19.68% (P＜0.01), respectively. It is concluded that the supplementation of lysine to the diets for lambs at the age below 150 days affected the voluntary intake and the digestibility of the diets, and increased the digestion amount of OM, NR and DWG of the lambs. The suitable levels of lysine in diets for 60 and 120 days’ Small Tail Han sheep male lambs were 2.0% and 0.8%, respectively. ［Chinese Journal of Animal Nutrition, 2010，22（4）:943-950］