Abstract: The concentration of andrographalide and dehydroandrographolide in plasma were determined by HPLC in two groups of rabbits after intragastric administration with ultramicropulverised powder or ordinary powder of Andrographis paniculata at a single dose （2 g·kg-1 BW） respectively. The plasma concentrationtime data of the two components above was analyzed by using Pharmaceutical Kinetics Software (PKS). Pharmacokinetic characteristics of the two groups were compared. The results showed that both the concentrationtime curves of andrographalide and dehydroandrographolide were confirmed to a two compartment model, compared with the ordinary powder. The area under concentrationtime (AUC) was raised by 5986%, time reaching the maximum consistency (Tpeak) was decreased by 714 minutes, and the maximum consistency (Cmax) was enlarged by 060% after the rabbits were administrated with ultramicropulverised powder. Dehydrographolide′s AUC was raised by 12464%, Tpeak was curtailed by 1433 minutes and Cmax was enlarged by 8834%. The results indicated that the ultromicropulverization method significantly increased the bioavailability of andrographalide and dehydroandrographolide of Andrographis paniculata.