The aims of this study intended to investigate the anti-inflammatory activity of the 70% ethanol extract from Scoparia dulcis (SDE) and betulinic acid on λ-carrageenan-induced paw edema in mice. The anti-inflammatory mechanism of SDE and betulinic acid was examined by detecting the levels of cyclooxygenase-2 (COX-2), nitric oxide (NO), tumor necrosis factor (TNF-α), interleukin-1β (IL-1β) and malondialdehyde (MDA) in the edema paw tissue and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd) in the liver. The betulinic acid content in SDE was detected by high performance liquid chromatography (HPLC). In the anti-inflammatory model, the results showed that SDE (0.5 and 1.0 g/kg) and betulinic acid (20 and 40 mg/kg) reduced the paw edema at 3, 4 and 5 h after λ-carrageenan administration. Moreover, SDE and betulinic acid affected the levels of COX-2, NO, TNF-α and IL1-β in the λ-carrageenan-induced edema paws. The activities of SOD, GPx and GRd in the liver tissue were increased and the MDA levels in the edema paws were decreased. It is suggested that SDE and betulinic acid possessed anti-inflammatory activities and the anti-inflammatory mechanisms appear to be related to the reduction of the levels of COX-2, NO, TNF-α and IL1-β in inflamed tissues, as well as the inhibition of MDA level via increasing the activities of SOD, GPx and GRd. The analytical result showed that the content of betulinic acid in SDE was 6.25 mg/g extract.