OBJECTIVE： To investigate the changes of extraction rates of forsythiaside A and forsythin in Forsythia suspensa compatible with other medicinal material of Menshi huwei formula before and after decoction. METHODS： HPLC method was used to determine the extraction amounts and to calculate the extraction rates of forsythiaside A and forsythin in F. suspensa （5 g×7 doses）， F. suspensa （5 g×7 doses） compatible with Pinelliae rhizoma praeparatum cum zingibere et alumine （PRZA）， Menshi huwei formula [including 6 ingredients as F. suspense （5 g×7 doses）， PRZA] after decocted with water. The determination was performed on Diamonsil C18 column with mobile phase consisted of acetonitrile-0.2％ formic acid solution （gradient elution）. The detection wavelength was set at 278 nm， and the column temperature was 30 ℃. The flow rate was 1.0 mL/min. RESULTS： The linear range of forsythiaside A and forsythin were 0.61-6.1， 0.246-2.46 μg （r＝0.999 7， 0.999 9）， respectively； RSDs of precision， stability （within 20 h） and reproducibility tests were all lower than 2％ （n＝6）. Average recovery rates were 96.10％-99.37％ （RSD≤2.36％，n＝6） respectively. In F. suspensa， extraction rates of forsythiaside A and forsythin were 96.90％ and 66.67％. In F. suspensa compatible with PRZA， extraction rates of them were 101.61％ and 54.55％. In Menshi huwei formula， extraction rates of them were 98.39％ and 84.85％. CONCLUSIONS： After F. suspensa is compatible with PRZA， the extraction rates of forsythiaside A is increased while forsythin is decreased. After compatible with other medicinal material in Menshi huwei formula， extraction rates of both are increased slightly.