Abstract: To investigate the effect of chlorogenic acid (CGA) extracted from Eucommia ulmoides Oliv. on blood hemorheological changes in hyperlipemia mice induced by high fat diet, fifty Kunming mice were randomly divided into 5 groups: negative control group, model control group, low dose (25 mg/kg BW), medium dose (50 mg/kg BW), and high dose (100 mg/kg BW) groups of CGA. The latter 4 groups were fed with high fat feed. CGA was given by gavage for 4 weeks. At the end of experiment, blood viscosity, plasma viscosity, hematocrit, erythrocyte indices of deformability, rigidity and aggregation, erythrocyte sedimentation rate and fibrinogen were assayed respectively. The antioxidant enzyme activities, MDA content, total antioxidant capabilities and hydroxyl radical scavenging rates in serum and liver were also measured. The blood viscosity, plasma viscosity, fibrinogen, erythrocyte sedimentation rate, erythrocyte indices of aggregation and rigidity were significantly reduced (P<0.05), erythrocyte index of deformability was significantly increased (P<0.05). The serum and liver SOD, GSH-Px level, total antioxidant capability and hydroxyl radical scavenging capacity were significantly increased (P<0.05), MDA production was significantly reduced (P<0.05). CGA extracted from E. ulmoides can effectively regulate the blood rheological parameters, and improve blood antioxidant capabilities and antioxidant enzyme activities. Through reduction in blood viscosity and erythrocyte of rigidity and aggregation, and enhancement in erythrocyte of deformability, CGA can improve the fluidity of cell membrane. Among them, the group at the dose of 50 mg/kg bw showed a relatively good effect.