OBJECTIVE： To establish a method for simultaneous determination of α-pinene， β-pinene， limonene and α-terpineol in volatile oil of Forsythia suspensa. METHODS： GC method was adopted. The determination was performed on HP-5 capillary column through temperature-programmed route. The inlet temperature was 230 ℃， and detector temperature was 250 ℃； split sampling was applied （split ratio of 8 ∶ 1）； the air flow rate was 300 mL/min， the hydrogen flow rate was 30   mL/min， the tail gas flow rate was 30 mL/min， and the injection volume was 1 μL. Using limonene as internal reference， relative correction factors of α-pinene， β-pinene and α-terpineol were established， and the reproducibility of relative correction factors were investigated by using different chromatographs and columns， and chromatographic peak location of components was measured. The contents of above components were calculated with QAMS， and then compared with the results of external standard method. RESULTS： The linear range of α-pinene， β-pinene， limonene and α-terpineol were 16.5-990.0， 38.1-2 287.5， 8.2-491.2， 2.4-142.5  μg/mL， respectively （r≥0.999 1）. RSDs of precision， reproducibility and stability tests were all lower than 3％ （n＝6）. Average recoveries were 99.7％-105.5％（RSD＜4％，n＝9）. Compared with limonene （1.00），the average relative correction factors of α-pinene， β-pinene and α-terpineol were 0.91，0.86 and 1.11（n＝3）； relative retention time were 0.69-0.74， 0.81-0.86， 1.25-1.35（RSD＜3％，n＝3）. By using different chromatographs and columns， RSDs of relative correction factors were 0.21％-4.65％（n＝6）. Compared with external standard method， determination results of above 4 components were consistent （the absolute value of relative error were all less than 7％）. CONCLUSIONS： QAMS can be used for simultaneous determination of 4 kinds of effective components in volatile oil from F. suspensa.