Objective: To dicuss processing mechanism of charred Rehmanniae Radix Praeparata with nourishing blood and hemostatic effect by screening its main active site. Method: Effective parts of charred Rehmanniae Radix Praeparata for hemostatic efficacy were screened with bleeding time (BT) and clotting time (CT) as indexes.Taking SD rats as the research object

by intraperitoneal injection of cyclophosphamide combined with tail bloodletting

and with 8% ethanol instead of free drinking water to establish rat model with blood deficiency and bleeding

the general physical signs and pathological tissue were observed

red blood cell count (RBC)

hemoglobin content (HGB) and white blood cell count (WBC) were determined;hemorrheological parameters and blood clotting tetrachoric[prothrombin time (PT)

thrombin time (TT)

activated partial thromboplastin time (APTT) and plasma fibrinogen (FIB)] were measured. Result: Compared with the blank group

charred Rehmanniae Radix Praeparata and its water part could shorten BT and CT of mice.Compared with the blank group

RBC

HGB and WBC of blood deficiency and bleeding model group rats decreased significantly;whole blood reduced viscosity under high and low shear increased;PT

TT and APTT prolonged and FIB increased.Compared with the model group

RBC

HGB and WBC of rats in the charred Rehmanniae Radix Praeparata group increased significantly;whole blood reducted viscosity and plasma viscosity under high

medium and low shear were decreased;PT

TT and APTT were shortened and FIB was reduced.Compared with the model group

RBC and HGB of rats in water part group increased;whole blood reduced viscosity under high shear was decreased;PT

TT and APTT were shortened and FIB was reduced. Conclusion: Charred Rehmanniae Radix Praeparata has a good nourishing blood and hemostatic effect for rat model with blood deficiency and bleeding.