Abstract: A high performance liquid chromatography(HPLC) method was developed for determinating contents of magnolol and honokiol in Lupo compound microemulsion formulation. Samples were extracted with methanol for 30 minutes after them were evaporated by solvent completely at temperature of 85 ℃, obtaining the filtering filtrate for determination. The chromatographic conditions were as follow: ZORBAX SB-C18(250 mm×4.6 mm, 5 μm) was used with the mobile phase of 0.5% phosphoric acid-methanol and the flow rate was 0.70 mL/min, at the detection wavelength of 294 nm, and the column temperature was 30 ℃. The results showed that the linear relationship of the magnolol density and peak areas was in the range of 0.074-0.518 μg/mL (r=0.999 7), and that of the honokiol was in the range of 0.152-1.064 μg/mL (r=0.999 8). The average recovery of magnolol was from 98.8% to 100.2% with RSD from 0.70% to 1.0% (n=6),and that of honokiol was from 98.5% to 99.5% with RSD from 0.90% to 1.1% (n=6). In five different batches of Lupo compound microemulsion formulation, the average content of magnolol was 2.692 4 mg/mL and that of honokiol was 1.216 5 mg/mL. The method is simple,quick, accurate and reproducible and can be used to determinate the magnolol and honokiol contents in Lupo compound microemulsion formulation.