There are many reports that dietary supplementation with plant polysaccharides in pigs might promote their growth, but little is known about the maternal effect of ginseng polysaccharides (GPS) on piglets' growth by dietary supplementation to pregnant and lactating sows. In the current study, the effects of dietary supplementation with GPS on the immunity of sows and growth of their piglets were investigated. Results showed no significant difference among the four groups in the total number of piglets, live piglets, weak piglets and birth weight of piglets, indicating the GPS-treatment has no adverse effect on reproduction. Furthermore, the weaning weight of the GPS-treated groups was higher than that of control group (P<0.05); among them, the addition of 200mg/kg dose has the best effect. Interestingly, GPS increased the total immunoglobulin G concentration in milk and serum of sows (P<0.05). The concentrations of interleukin (IL)-2, IL-6, tumor necrosis factor (TNF)-, and interferon- in milk and serum of sows were also increased in the experimental groups relative to the control (P<0.05). Meanwhile, maternal supplementation of GPS significantly increased IL-2 and TNF- concentration in the piglets' serum of the experimental groups relative to control (P<0.05). GPS (200mg/kg) significantly increased the glutathione peroxidase activity in milk and serum (P<0.05), while the concentrations of malondialdehyde were significantly reduced (P<0.05). The present results indicated that GPS supplementation during late pregnancy and lactation improved immunity-related bio-molecular levels in sow serum and milk, which may be further beneficial to piglet health and growth through biological transmission effects.