This study was conducted to explore the possibility of dietary supplementation with fermented distiller's grains. We analyzed the effects of dietary substitution in a basal diet with different ratios of fermented Mao-tai lees (FML) on plasma biochemical parameters and antioxidant indices of finishing pigs. A total of 48 healthy Duroc×Large White×Landrace barrows with average body weight (BW) of (39.95±2.15) kg were used and randomly allocated to one of four groups with 12 replicates per group and 1 pig in each replicate, which were fed in an automatic feeding system. The pigs in the control group were fed a basal diet, and those in experiment groups were fed a diet with 5%, 10% or 15% FML to replace the equal ratio of basal diet, respectively. Eight pigs per group were randomly selected when they gained 60, 75 and 110 kg of average BW, and blood samples were collected by precaval vein. The plasma was obtained by centrifuging for analyzing biochemical parameters and antioxidant indices. The results showed that, in pigs with 60 kg BW, compared with the control group, the plasma low density lipoprotein-cholesterol (LDH-C) content and α-amylase (α-AMY) activity were significantly increased (P<0.05), while the plasma alanine aminotransferase (ALT) activity was significantly decreased (P<0.05) in 5% substituted group; the plasma α-AMY activity was significantly increased (P<0.05), while the plasma glucose (GLU) content and ALT activity were significantly decreased (P<0.05) in 10% substituted group; the plasma triglyceride content, glutathione peroxidase (GSH-Px) activity and glutathione (GSH) content were significantly increased (P<0.05), while the plasma malonaldehyde (MDA) content was significantly decreased (P<0.05) in 15% substituted group. In pigs with 75 kg BW, compared with the control group, the plasma LDL-C content and catalase (CAT) activity were significantly increased (P<0.05), while the plasma high density lipoprotein-cholesterol (HDL-C) content was significantly decreased (P<0.05) in 5% substituted group; the plasma LDL-C content and activities of CAT and GSH-Px were significantly increased (P<0.05), while the plasma activities of aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were significantly decreased (P<0.05) in 10% substituted group; the plasma activities of CAT, superoxide dismutase (SOD) and GSH-Px were significantly increased (P<0.05), while the plasma contents of urea nitrogen (UN), HDL-C and GLU as well as activities of α-AMY, AST and LDH were significantly decreased (P<0.05) in 15% substituted group. In pigs with 110 kg BW, compared with the control group, the plasma ALT activity was significantly decreased (P<0.05), the plasma α-AMY activity was significantly increased (P<0.05), while the plasma UN content was significantly decreased (P<0.05) in 5% substituted group; the plasma total protein content were significantly increased (P<0.05), while the plasma UN content and ALT activity were significantly decreased (P<0.05) in 10% and 15% substituted groups. In addition, the plasma AST activity in 15% substituted group was significantly decreased (P<0.05). Collectively, these findings suggest that dietary FML supplementation to replace parts of basal diet can alter the metabolism and antioxidant capacity of finishing pigs, depending on the replacement ratio in diet; dietary supplementation with 15% FML to replace the equal ratio of basal diet improves the nitrogen metabolism of pigs with 75 and 110 kg BW and enhances the antioxidant capacity of pigs with 60 kg BW.