The research was conducted to study the effects and antioxidation mechanisms of maternal dietary arginine levels on small intestinal mucosa development of suckling piglets. Thirty-six Yorkshire×Landrace multiparous sows were selected and randomly assigned into three groups including 0.82% arginine group (n=12), 1.23% arginine group (n=12) and 1.64% arginine group (n=12), and were fed diets containing 0.82%, 1.23% and 1.64% arginine, respectively. The research was done from day 4 to 22 after parturition. Results showed that villous height of duodenum of suckling piglet was significantly higher in 1.23% and 1.64% arginine groups than that in 0.82% arginine group (P<0.05), and crypt depth of duodenum and ileum of suckling piglet was significantly lower in 1.64% arginine group compared with 0.82% arginine group (P<0.05), also crypt depth of jejunum of suckling piglet in 1.23% and 1.64% arginine groups was significantly lower than that in 0.82% arginine group (P<0.05). Lactase and alkaline phosphatase activities in duodenum and jejunum of suckling piglet were significantly higher in 1.64% arginine group compared with 0.82% arginine group (P<0.05). Glutathione peroxides (GSH-Px) activity of intestinal mucosa of suckling piglet was increased with the rise of maternal dietary arginine level, which was significantly different between every two groups in duodenum of suckling piglet (P<0.05), and significantly improved in jejunum and ileum of suckling piglet in 1.64% arginine group compared with 0.82% arginine group (P<0.05). The superoxide dismutase (SOD) activities in duodenum, jejunum and ileum of suckling piglet were significantly higher in 1.64% arginine group than those in 0.82% arginine group (P<0.05). The duodenum malonaldehyde (MDA) content of suckling piglet was significantly lower in 1.23% and 1.64% arginine groups compared with 0.82% arginine group (P<0.05), and the jejunum MDA content was significantly lower in 1.64% arginine group in contrast to 0.82% arginine group (P<0.05). These results indicate that indicate maternal dietary arginine level can ameliorate small intestinal mucosa development of suckling piglet, and its mechanism might be related to better antioxidant capacity with higher dietary arginine level.［Chinese Journal of Animal Nutrition, 2010，22（4）:870-878］