Objective To study the pharmacokinetics of aristolochic acid A in Radix Aristolochiae and the compound preparation of Guanxinsuhe Capsule in mice in vivo after single-dose oral administration and observe the difference of aristolochic acid A absorption and distribution. Methods Aristolochic acid A assay was performed by RP-HPLC on a Waters apparatus with a DiamonsilTM C18 column (250 mm × 4.6mm, 5 μm), a mobil phase: a mixture of methanol-water-acetic acid (72: 27 : 1), flow rate: 1.0 mL/min, detection wavelength: 315 nm, and column temperature: 20 ℃. Results Mice were given Radix Aristolochiae and Guanxinsuhe Capsule by ig at the same level of 2. 5 mg/kg of aristolochic acid A, respectively, which were suspended in 0. 3% CMC-Na solution. Plasma concentrations were determined by RPHPLC. After single-dose ig administration of Radix Aristolochiae or Guanxinsuhe Capsule to mice, the mean plasma concentration-time courses of aristolochic acid A obtained fitted the one-compartment model.The main pharmacokinetic parameters of aristolochic acid A in Radix Aristolochiae, t1/2ka, t1/2 ke, tmax,AUC, Cmax are 5. 103 min, 43. 63 min, 17.89 min, 80. 45 (μg · min)/mL, and 0. 916 8 μg/mL; the rela tive pharmacokinetic parameters in Guanxinsuhe Capsule are 5. 294 min, 43.50 min, 18. 32 min, 33.08(μg · min)/mL, and 0. 381 8 μg/mL. Conclusion The Cmax of aristolochic acid A in Guanxinsuhe Capsule is significantly less than that in Radix Aristolochiae, which indicates that the compound compability could decrease the absorption of aristolochiae acid A.