Abstract: OBJECTIVE To investigate the effects of the compatibility of Eriobotryae Folium and honey-fried Fritillaria Cirrhosa on pharmacokinetic changes of rutin, quercetin, kaempferol by LC-MS/MS method. METHODS The plasma samples were extracted by solid-phase extraction. The LC column was Waters XTerra MS C₁₈ (150 mm×2.1 mm, 3.5 μm). The mobile phase comprised of acetonitrile and water containing 0.1% formic acid. The quantification was obtained by scanning with multiple reaction monitoring (MRM) via the negative electrospray ionization (ESI^-) source. The rats were randomly divided into two groups and orally administered with Eriobotryae Folium or Eriobotryae Folium-Fritillaria Cirrhosa decoction. RESULTS The correlation coefficients were over 0.998, indicating excellent linearity. The values of precision, accuracy, matrix effect and average recovery were acceptable. Compared with single herb group, the C_max and AUC_0-t were decreased, the t_1/2 were extended in herbal pair group. CONCLUSION After combining the herbs, the bioavailability of rutin, quercetin and kaempferol are reduced, the elimination of them delays, and the dwell time increases.