OBJECTIVE:To study and compare the volatile constituents in Forsythia suspensa and old F. suspensa. METH-ODS:Steam distillation method was adopted to extract volatile oil. GC-MS was adopted to determine the content of volatile oil:the chromatographic conditions:the column was HP-5MS,inlet temperature was 200 ℃,the carrier gas was nitrogen,split ratio was 20 to 1,by programmed temperature,flow rate was 1 ml/min,the injection volume was 1 μl;MS conditions:ion source was electric bombardment ionization source,electron energy was 70 eV,the interface temperature was 280 ℃,ion source temperature was 230 ℃,quadrupole temperature was 150 ℃,electron multiplier voltage was 2 300 V,and mass scanning range was 29-350 amu. RESULTS:The extraction yield order of volatile oil was that F. suspensa heart was higher than F. suspensa,followed by F. suspensa shell and old F. suspensa;there were 18 common peaks in the volatile oil,and the content of β-pinene was the maxi-mum,followed by α-pinene,β-phellandrene,terpinen-4-ol and terpinene;in addition,4-methylene-1-cyclohexanone,3-cyclohex-ene-1-methanol,cumene formaldehyde,1,7-trimethyl-4-methylenedecahydro,palmitic acid,nutmeg aldehyde can only be detected in the volatile oil of old F. suspensa;while α-phellandrene,ocimene,α-terpineol,α-pinocarvone,cis-piperitol,bornyl acetate,α-cubebene and germacrene D can only present in F. suspensa. CONCLUSIONS:The main chemical components in the volatile oil of F. suspensa and old F. suspensa are basically the same,but there are also some differences. The discovery can provide some ba-sis for the material basic research in the pharmacodynamic differences of F. suspensa.