The flavoniods and polyphenols were separated from Eucommia ulmoids leaves by resin, at last, four components containing different ingredients were gotten. Two components, one of which contained more polyphenols, and one of which contained more flavoniods (EUII), were chosen for in vivo antioxidation test. The antioxidation activity in vivo was studied by measuring the content of malondialchehyche (MDA), and superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity in mice orally administrated by EUI and EUII. The results showed that 20% ethanol elution solution (EUI) contained more polyphenols and 60% ethanol elution solution (EUII) contained more flavoniods; by comparing with negative control (NC) group, EUI, which contained more polyphenols, showed more obvious antioxidation activities in vivo. The results also meant that polyphenols was the leading working material for Eucommia ulmoids leaves in antioxidation in vivo.