Abstract: In order to meet the need of drug supervision, an analytical method was developed to determine the preservatives and antioxidants of medicines and healthcare dietetic liquid in the matrix of water, alcohol and other liquid by gas chromatography-mass spectrometry (GC/MS). Selected ion monitoring (SIM) technology was used in this method. 28 preservatives, including acetonchloroform hemihydrate, phenol, benzyl alcohol, sorbic acid, benzoic acid, methylisothiazolinone, dehydroacetic acid, ethoxyquin, hexyl resorcinol, parabens etc, and 3 antioxidants, including TBHQ, BHA, BHT, which were used in eye drops, injection, drops, paint, and healthcare dietetic liquid, were able to be determined by this method simultaneously. Good linearity is obtained in the range of 0.005—1 mg/L with the correlation coefficients of 0.998 5—0.999 9. The mean recoveries of all the preservatives in the range of 0.02—0.30 mg/L are between 73.6% and 109.9%, and the relative standard deiations are between 1.2% and 13.6%. The limits of detection(LODs) are in the range of 0.001—0.008 mg/L, and the limits of quantification（LOQs）are in the range of 0.003—0.020 mg/L. The method is used in the analysis of multiple batches of sample. The result indicates that it is sensitive, accurate, stable, reliable and widely usable.