Abstract: OBJECTIVE To comparative investigate the effect of the ultrafiltrate of Astragali Radix (RA-U) and the ultrafiltrate of Hedyseri Radix (RH-U) on hemorheology and related regulatory factors in rat stasis model combined transient cerebral ischemia. METHODS Using im. dexamethasone and ligating common carotid artery, the model of rat’s cerebral ischemia was established to evaluate the effects of the RA-U and the RH-U through detecting the levels of blood viscosity and vasoactive substance in serum. RESULTS The RA-U(1.32 g·kg^-1) and the RH-U (1.68 g·kg^-1) could degrade blood viscosity and NO, NOS and ET in serum, and upgrade calcitonin gene related peptide remarkably (P<0.05 or 0.01). CONCLUSION The RA-U and the RH-U have some protective effects on cerebral ischemia in rats, and one of the mechanisms is improving hemorheology and hemodynamics.