Abstract: High performance liquid chromatography(HPLC) was applied to determine the concentrations of plamsa baicalin in two groups of rabbits after administering the ultramicro-pulverised powder and the ordinary powder of HLJDS (in water suspension) by gastrogavage respectively. The plasma concentrationtime data of baicalin were dealt with Pharmaceutical Kinetics Software (PKS). Pharmacokinetics characteristics of both the ultramicro-pulverised powder and ordinary powder of HLJDS were compared. The results showed that the best pharmacokinetic model of baicalin in either group was two-compartment open model.The main pharmacokinetic parameters of baicalin of ultramicropulverised powder were as follows: K_a=0.497 h^-1, t_1/2α=2.556 h，t_1/2β=8.46 h，AUC_0→∞=3.401 μg·h/mL，V_d=6.752 L/kg, T_peak=3.005 h， C_max=0.311 μg/mL；The main pharmacokinetic parameters of baicalin of the ordinary powder were as follows:K_a=0.419 h^-1, t_1/2α=2.74 h，t_1/2β=5.83 h，AUC_0→∞=2.611 μg·h/mL，V_d =12.890 L/kg，T_peak=3.645 h，C_max=0.215 μg/mL. As compared to the baicalin from ordinary powder, the relative bioavailability of baicalin from ultramicro-pulverised powder was increased by 30.26%. These data presented above indicated that the bioavailbility of baicalin from HLJDS could be greatly improved after processing and preparing by the technique of ultromicro-pulverization.