Objective To establish a lipoic acid synthase gene-modified mouse model and detect their antioxidant capacity. Methods Mice with a loxP-modified 3′-UTR region of the lipoic acid synthase gene were hybridized with EIIa- Cre mice. Lias^{L/ +} mice were identified from their offspring genotypes, and further propagated. Three genotypes of offspring were identified. Ten 8-week-old male mice with Lias^{L/ L} and Lias^{+ / +} genotypes were randomly selected. After weighing and anesthesia, blood was collected via the femoral artery, and then the kidneys, livers and lungs were collected and weighed. Western Blot and immunohistochemistry were used to detect expression levels of lipoic acid synthase (LIAS) protein in kidney, liver and lung tissue. Serum was collected to detect total antioxidant capacity (TAC). The total protein of tissue homogenates from kidney, liver and lung samples were used to detect the activities of superoxide dismutase and catalase, and the content of malondialdehyde. Results The expression levels of Lias in kidney, liver and lung samples from Lias^{L/ L} mice were significantly lower than those from Lias^{+ / +} mice by semi-quantitative western blotting and immunohistochemical analysis (P< 0. 05). Compared with the Lias^{+ / +} group, serum levels of TAC and enzyme activities of superoxide dismutase and catalase in kidney, liver and lung samples were decreased, and the malondialdehyde level increased in the Lias^{L/ L} group (P< 0. 05). Conclusions Kidney, liver and lung expression levels of Lias were lower in mice with a modified 3′- UTR region of Lias than those of wild-type mice, with corresponding oxidative damage observed in these organs.