Abstract: This study was conducted to investigate the effects and potential mechanisms of dietary Ncarbamylglutamate (NCG) supplementation during late gestation on the reproductive performance of sows. Thirtytwo Landrace × Large White sows on d 80 of gestation were assigned randomly to 4 groups (control group and experimental group 1, 2, 3), 8 replicates in each group. Sows in the control group were fed with basic diet, and those in the experimental groups were fed with basic diet supplemented with 0.04%, 0.08% and 0.12% NCG. Blood samples were obtained on d 110 of gestation to examine the plasma concentration of free amino acids, NO, NOS, hormones and biochemical indices. The results showed that supplementation with 0.08% NCG increased the number of piglets born alive by 11.75% (10.75 vs. 9.62, 0.05<P<0.1) and live litter birth weight by 13.23% (16.52 kg vs. 14.59 kg,P<0.05), decreased piglets born dead per litter by 57.14% (0.75 vs. 1.75,P<0.05) and plasma urea nitrogen concentration compared with the control group, and increased plasma concentration of arginine, NO, NOS, growth hormone and Zn+ too (P<0.05). 0.04% and 0.12% NCG enhanced the reproductive performance of sows. The result suggest that dietary NCG supplementation could enhance reproductive performance of sows, and the potential mechanisms is that the supplemented NCG increases endogenous arginine synthesis in sows, so as to improve intrauterine environment and fetal nutrition, and guarantee fetus survival and growth.