This experiment was conducted to study the effects of weaning age on growth performance and serum biochemical indices of Wuzhishan piglets. A total of 96 Wuzhishan piglets with the similar age (±1 day) and the average body weight of (0.56±0.07) kg were randomly divided into 4 groups with 4 replicates per group and 6 piglets per replicate. Piglets in those 4 groups were weaned at the age of 21, 28, 35 and 42 days, respectively. The experiment was carried out from 8 to 56 days of age, and body weight, feed intake and serum biochemical indices were regularly determined. The results showed that the average daily gain (ADG) of piglets in the four groups was decreased to varying degrees after weaning. The earlier the weaning age, the more decrease of ADG. The ADG in 35-day-old and 42-day-old weaned groups was significantly higher than that of 21-day-old weaned group at the age of 21 to 28 days, 28 to 35 days, 35 to 42 days and 49 to 56 days (P<0.05). Weaning could significantly increase the average daily feed intake (ADFI) of piglets in the four groups, and the ADFI of piglets had no significant difference among the four groups at 42 days of age (P>0.05). The contents of total protein (TP), albumin (ALB), immunoglobulin G (IgG), immunoglobulin M (IgM), and the activities of glutamic oxalacetic transaminase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in serum in 21-day-old, 28-day-old and 35-day-old weaned groups were significantly changed at 7 days post-weaning (P<0.05), and the largest fluctuation was observed in 21-day-old weaned group. Compared with the 35-day-old and 42-day-old weaned groups, the serum TP, ALB, IgG and IgM contents were significantly decreased (P<0.05), and the serum ALT, AST and LDH activities were significantly increased in 21-day-old weaned group (P<0.05). The serum TP, IgG and IgM contents were still lower in 21-day-old weaned group than 35-day-old and 42-day-old weaned groups at 56 days of age (P<0.05). The serum triglyceride (TG) and cholesterol contents (CHOL) contents in 21-day-old weaned group were significantly changed during 28 to 56 days of age (P<0.05), while these had no significant difference during whole experimental period in the 35-day-old and 42-day-old weaned groups (P>0.05). In addition to significant differences existed at the age of 42 days (P<0.05), there were no significant difference in serum TP, ALB, IgG and IgM contents, and AST, ALT and LDH activities between the 35-day-old and 42-day-old weaned groups (P>0.05). It is suggested that Wuzhishan piglets weaned at 35 or 42 days of age are better than those weaned at 21 days of age in growth performance, serum biochemical indices and immune function.