Abstract: The chocolate sample was extracted with ethyl acetate and dried,and dissolved with saturated acetonitrile and defatted with n-hexane. The contents of vanillin,TBHQ and caffeine in sample solution were determined by GC-MS. The HP-5MS capillary column was used for GC separation and the SIM mode was adopted in MS determination. The values of detection limit (3S/N) of vanillin,TBHQ and caffeine found were 0.04,0.05,0.02 mg·kg-1. Recovery was tested by standard addition method,giving values of recovery in the range from 86.1% to 99.9%,with their RSD′s (n=11) 2.01%,1.10% and 1.68%,respectively.