Objectives The effects of extract from Codonopsis pilosula on promoting the growth and intestinal health of weaned piglets were studied to provide a basis for improving the health of piglets and enhancing the efficiency of farming pigs. Methods 24 weaned piglets of the same sex and breed at 21 days of age were selected and randomly divided into 3 groups, with 8 replicates in each group. The control group was fed a basic diet, while the experimental groups were divided into a low-dose group and a high-dose group, with 0.1% and 0.2% extract from Codonopsis pilosula added to the basic diet, respectively. The growth performance, biochemical indexes in serum and the structure of small intestine were measured during the experiment. Results The average daily gain of weight in piglets in the low-dose and high-dose groups of extract from Codonopsis pilosula significantly increased by 11.28% and 20.00%, and the ratio of feed to weight significantly decreased by 6.82% and 9.85% compared with the control group. The activity of alanine aminotransferase in the serum of weaned piglets in the low-dose group and high-dose group significantly decreased by 36.28% and 39.24%, and the activity of lactate dehydrogenase significantly decreased by 28.07% and 35.22%. The ratio of glutamic straw to grain C in the experimental group decreased significantly. The addition of extract from Codonopsis pilosula to the feed significantly increased the villus height of the duodenum, jejunum, and ileum, and the ratio of pile to hide in duodenum and jejunum of weaned piglets. But it has no significant effect on the organ index of weaned piglets. Conclusions Adding extract from Codonopsis pilosula to the feed can significantly improve the growth performance, reduce liver damage, and promote intestinal health of weaned piglets. The best effect was achieved with a 0.2% addition ratio.