Ginsenoside Rb1 (GRb1), one of the principle active ingredients of Panax ginseng, exerts multiple pharmacological activities to fight fatigue. In the present study, we investigate the anti-fatigue effect of GRb1 on postoperative fatigue syndrome (POFS) in a rat model induced by major small intestinal resection. GRb1 (10 mg/kg) was administrated intraperitoneally once daily for 1, 3, 7, and 10 d from the operation day. Anti-fatigue effect was assessed by grasping test and biochemical parameters in blood or skeletal muscle were determined by autoanalyzer or commercially available kits. Transmission electron microscope was applied to observe the ultra microstructure of skeletal muscles. The results revealed that GRb1 significantly enhanced rat maximum grip strength with POFS. Similarly, negative alterations in biochemical parameters (lactic acid, hepatic glycogen, muscle glycogen and malondialdehyde) of POFS rats were improved by GRb1. In addition, GRb1 also increased the activity of lactate dehydrogenase and superoxide dismutase in POFS. No significant differences of levels of blood urea nitrogen and ultra microstructure of skeletal muscles were found between the POFS and GRb1 treatment rats. The potent anti-fatigue effect of GRb1 on POFS might be achieved through improvement of energy metabolism and suppression of skeletal muscle oxidative stress.