Objective To study the influence of swimming training for different periods on rat liver function, and to evaluate the quality of exercise-induced fatigue rat model established by swimming training for different periods. Methods Forty SD rats were randomly divided into 5 groups, namely blank group, and 7-, 14-, 21-and 28-day exercise groups, 8 rats in each group. Rats in the blank group were fed with normal diet, but were not given exercise training. The other groups were given exercise training for 7, 14, 21 and 28 days respectively, two times a day, 15 minutes every time and with 10-minute resting interval between the two times. At the last day of the experiment, all rats were executed by neck dislocation for the sampling of blood and liver tissues, and then the serum contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. And the contents of total anti-oxidization capacity (T-AOC), malondialdehyde (MDA), lactic acid (LA), lactate dehydrogenase (LDH) and glucose (Glu) in liver tissues were also examined. Results Compared with the blank group, the contents of ALT and AST were increased in 7-, 14-, 21-, and 28-day exercise groups, especially in 21-and 28-day exercise groups (P<0.01) . The contents of T-AOC and MDA were increased in 7-, 14-, 21-, and 28-day exercise groups (P<0.01), the effects on T-AOC in the 21-and 28-day exercise groups and on MDA in the 28-day exercise group being more obvious (P<0.05 or P<0.01) . The LA content and LDH activity were increased and the glycogen was decreased in the liver tissues of 7-, 14-, 21-, and 28-day exercise groups, and the increase of LA content in 21- and 28-day exercise groups and that of LDH activity in 28-day exercise groups were more significant ( P<0.05 or P<0.01). The hepatic glycogen content in 14-, 21-, and 28-day exercise groups were lower than that in the other groups (P<0.01). Conclusion With hepatic function injury in exercise-induced fatigue as the criteria, the exercise-induced fatigue rat model has been successfully established in this study, and the model established by swimming training for 21 and 28 days is more steady.