Feed is the most expensive input in commercial pork production. In order to reduce feed costs, using high-fiber ingredients has become a common practice. Moderate levels of fiber can maintain intestinal physiological function and promote intestinal health. Oxidative stress is linked to impaired nutrient absorption and growth performance. This study investigated the effects of high-fiber (HF, 6% crude fiber) and low-fiber (LF, 3% crude fiber) diets on growth performance and intestinal oxidative stress parameters in growing-finishing pigs. Forty growing pigs (27.07 ± 1.26 kg BW) were randomly assigned to 2 treatments with 10 replicates of 2 pigs per pen. Pigs were weighed on days 35, 42 and 70. The feed intake was recorded daily to calculate growth performance parameters. On day 70, eight pigs in each treatment group were randomly selected and euthanized to obtain jejunum to measure oxidative stress status. Pigs fed an HF diet were heavier than those fed an LF diet on days 35, 42 and 70 (P < 0.05). During the whole feeding period, pigs fed an HF diet had higher average daily gain than those fed an LF diet (P < 0.05). The LF diet resulted in increased levels of malondialdehyde (P < 0.05) in the jejunum, suggesting that the LF diet contributed to oxidative stress in the jejunum. The LF diet also led to a significant increase in glutathione and oxidized glutathione levels (P < 0.05) in the jejunum, indicating that pigs fed an LF diet needed to produce more antioxidant substances to cope with oxidative stress in the intestine. This was accompanied by a significant increase in glutamate-cysteine ligase in the jejunum of the LF group (P < 0.05).