This experiment was aimed to investigate the effects of dietary lysine levels on the growth performance, nitrogen utilization and body deposition of the neonatal piglets, and to determine dietary lysine requirement of the neonatal piglets. In this experiment, a single-factor random test design was used, forty-six 4-day-old neonatal piglets (Duroc×Landrace×Yorkshire) with (1.90±0.05) kg were selected, from which 40 piglets were randomly assigned to 5 dietary groups (4 replicates per group, and 2 piglets per replicate) according to litter and body weight, and the other six piglets were slaughtered to determine the body composition at the trial beginning. The dietary lysine levels were designed as: 1.27% (the control), 1.37%, 1.47%, 1.57% and 1.67%, respectively. The results showed as follows: 1) the use of 1.47%, 1.57%, and 1.67% lysine diets increased BW of piglets at 21-day-old and average daily gain (ADG) at (15～21)-day-old and (4～21)-day-old (P<0.05), and ADG in 1.57% group was the highest. At (15～21)-day-old and (4～21)-day-old, average daily feed intake in 1.57% and 1.67% groups were significantly higher than that in the control group (P<0.05). Supplementing 1.37%～1.67% lysine significantly decreased F/G (P<0.05); 2) the biological value of nitrogen in 1.47% to 1.67% groups were significantly higher than that in 1.27% group and 1.37% group (P<0.05); 3) dietary lysine levels had no influence on energy and fat deposition of piglets (P>0.05). Protein deposition was higher in 1.47%～1.67% groups than those in 1.27%～1.37% groups (P<0.05), where the highest value was in 1.67% group. From these results, it could be concluded that optimal dietary lysine level for neonatal piglet at (4～21)-day-old was 1.57%, that is, 73.1 g/kg CP or 0.85 g/MJ DE, or 2.43 g/d.［Chinese Journal of Animal Nutrition, 2010，22（2）:272-277］